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Discussion document
Citation: Advisory Committee on Assisted Reproductive Technology. 2008. Consultation on the Use of Frozen Eggs in Fertility Treatment:Discussion document.Wellington: Advisory Committee on Assisted Reproductive Technology.
Published in July 2008by the Advisory Committee on Assisted Reproductive Technology.PO Box 5013, Wellington, New Zealand
ISBN: 978-0-478-31781-7 (print)ISBN: 978-0-478-31782-4 (online)HP4618
This document is available on the ACART website:http://www.acart.health.govt.nz
Chairs foreword
Human assisted reproductive technologies are advancing rapidly. These technologies offer many potential benefits to infertile couples, but there are also uncertainties and risks. The Advisory Committee on Assisted Reproductive Technology (ACART) has been established to formulate policy advice specific to New Zealand in relation to this controversial field.
The collection and freezing of eggs was declared to be an established procedure in New Zealand in 2005. This means that eggs can be collected and frozen routinely in fertility clinics without requiring case-by-case approval by the Ethics Committee on Assisted Reproductive Technology (ECART).
When ACART was established, the then Minister of Health, Hon Annette King, asked, among other things, for advice on the use of frozen eggs in fertility treatment. Before ACART advises the Minister of Health, it is required to consult on the proposed advice.
ACART proposes that the use of frozen eggs in fertility treatment become an established procedure. The reasons for this are set out in the following pages of this discussion document.
Please take the time to consider the questions included in this document. We would welcome your comments on these, or any other aspect of the document. Although ACART has set out its proposed advice to the Minister, it is open to changing its views. Your comments will help ACART to finalise its recommendations to the Minister on the use of frozen eggs in fertility treatment.
EMBED MSPhotoEd.3
Sylvia Rumball
Chair, Advisory Committee on Assisted Reproductive Technology
How to have your say
Your feedback is important to help ACART finalise its advice on the use of frozen eggs. Please take this opportunity to have your say. You may make a submission on your own behalf or as a member of an organisation. A summary of submissions will be released along with ACARTs advice to the Minister of Health.
ACART welcomes your views on any or all of the issues raised. However, there are some key questions we would like you to think about and comment on. These questions are set out in a detachable submission form at the back of this document.
You can contribute your views by:
1. emailing a completed submission form or your comments to HYPERLINK "mailto:acart@moh.govt" acart@moh.govt
2. writing down your views on the submission form and posting it to:
ACART Secretariat
PO Box 5013
Wellington.
The closing date for submissions is 5 September 2008.
All submissions will be considered before ACARTs advice to the Minister of Health is finalised.
Additional copies of this discussion paper are available from the ACART website HYPERLINK "http://www.acart.health.govt.nz" www.acart.health.govt.nz or from:
Wickliffe Press
PO Box 932
Dunedin
Phone (04) 496 2277
Email: HYPERLINK "mailto:moh@wickliffe.co.nz" moh@wickliffe.co.nz
When ordering this discussion paper from Wickliffe, please quote HP 4618.
Contents
TOC \o "1-2" Executive summary PAGEREF _Toc202167116 \h vi
1 Introduction PAGEREF _Toc202167117 \h 1
ACARTs role PAGEREF _Toc202167118 \h 1
Scope of this document PAGEREF _Toc202167119 \h 1
Abbreviations and terms used PAGEREF _Toc202167120 \h 2
2 Information about egg freezing PAGEREF _Toc202167121 \h 3
What is an egg? PAGEREF _Toc202167122 \h 3
Egg freezing as a procedure PAGEREF _Toc202167123 \h 3
Egg freezing in New Zealand PAGEREF _Toc202167124 \h 3
Options for the use of frozen eggs PAGEREF _Toc202167125 \h 4
3 Assessment of known risks and benefits to health associated with the use of frozen eggs PAGEREF _Toc202167126 \h 5
Risks PAGEREF _Toc202167127 \h 5
Benefits PAGEREF _Toc202167128 \h 7
Monitoring PAGEREF _Toc202167129 \h 7
4 Acceptability of the risks associated with the use of frozen eggs PAGEREF _Toc202167130 \h 8
5 Ethical Analysis PAGEREF _Toc202167131 \h 9
Informed consent PAGEREF _Toc202167132 \h 9
Posthumous use of frozen eggs P A G E R E F _ T o c 2 0 2 1 6 7 1 3 3 \ h 9
D o n a t i n g f r o z e n e g g s f o r t r e a t m e n t p u r p o s e s P A G E R E F _ T o c 2 0 2 1 6 7 1 3 4 \ h 1 0
M o r i p e r s p e c t i v e s P A G E R E F _ T o c 2 0 2 1 6 7 1 3 5 \ h 1 0
H u m a n r i g h t s i s s u e s P A G E R E F _ T o c 2 0 2 1 6 7 1 3 6 \ h 1 1
E q u i t y P A G E R E F _ T o c 2 0 2 1 6 7 1 3 7 \ h 1 1
U s e of eggs for social reasons PAGEREF _Toc202167138 \h 12
6 Conclusion: Proposed advice to the Minister PAGEREF _Toc202167139 \h 13
Glossary PAGEREF _Toc202167140 \h 14
Appendices
Appendix 1: Report on Egg Freezing for ACART PAGEREF _Toc202167141 \h 16
Appendix 2: Risk Assessment of the Use of Frozen Eggs PAGEREF _Toc202167149 \h 39
Appendix 3: Members of ACART PAGEREF _Toc202167160 \h 46
Submission Form PAGEREF _Toc202167173 \h 51
Executive summary
In June 2005 the collection and cryopreservation (freezing) of human eggs was declared to be an established procedure, meaning that it could be routinely offered by fertility clinics. However, the subsequent use of frozen eggs was specifically excluded from this established procedure because the risks could not be adequately assessed due to the novelty of the technique.
The Advisory Committee on Assisted Reproductive Technology (ACART) has reviewed recent evidence and considered the risks, benefits and ethical issues associated with the use of frozen eggs. ACART proposes to recommend to the Minister that the use of frozen eggs now become an established procedure, for the following reasons:
Evidence suggests that the risks to a resulting child associated with the use of frozen eggs are no greater than the risks associated with the use of frozen embryos or in-vitro fertilisation (IVF) generally, given that damaged eggs will be identified and discarded or will fail to fertilise.
Egg freezing and subsequent use is the only option available for preserving the fertility of some women, particularly those undergoing cancer treatment.
Egg freezing and subsequent use offers an alternative to those who, for religious or spiritual reasons, find the freezing of embryos unacceptable.
Egg freezing and subsequent use may also have benefits where embryos cannot be formed due to the absence of sperm for fertilisation.
The few ethical issues associated with the use of frozen eggs can be better managed in direct discussions between clinicians and patients.
ACART considers that if the use of frozen eggs in fertility treatment is approved as an established procedure, it will be important to monitor the outcomes for children born in New Zealand from the use of frozen eggs. ACART has the responsibility for such monitoring.
1 Introduction
ACARTs role
ACARTs role under the Human Assisted Reproductive Technology Act 2004 (HART Act 2004) is to:
issue guidelines and advice to the Ethics Committee on Assisted Reproductive Technology (ECART) on any matter relating to any kind of assisted reproductive procedure or human reproductive research
provide the Minister with advice on aspects of, or issues arising out of, different kinds of assisted reproductive procedures or human reproductive research
monitor the application and health outcomes of assisted reproductive procedures and established procedures and developments in human reproductive research.
Scope of this document
When ACART was established, the then Minister of Health, Hon Annette King, asked ACART, among other things, for advice on the use of eggs frozen at the mature stage, following collection for fertility treatment. Under the HART Act 2004 ACART could recommend that the use of frozen eggs for fertility treatment be:
an established procedure
subject to ethical approval on a case-by-case basis (therefore requiring guidelines)
subject to a moratorium
prohibited.
An established procedure is a procedure that is declared established under section6 of the HART Act 2004 and that can be routinely undertaken by fertility clinics, without the clinic having to seek ethical approval from ECART on a case-by-case basis.
ACART has decided that when it considers any new technology it will follow the process set out in the HART Act 2004 for determining if a procedure should become an established procedure. In giving its advice to the Minister, ACART is required by the HART Act 2004 to provide the Minister with a report that sets out:
information about the procedure or treatment
an assessment, drawn from published and peer-reviewed research, of the known risks and benefits to health of the procedure or treatment
advice on whether, in its expert opinion, the known risks to health resulting from the procedure or treatment fall within a level of risk that is acceptable in New Zealand
an ethical analysis of the procedure or treatment
advice on whether, in its expert opinion, the Minister should recommend that the procedure or treatment be declared an established procedure.
This document follows the above format.
Note that the established procedure of egg collection and freezing is outside the scope of this document. Also outside the scope of the document is the use of eggs frozen at the very immature stage in pieces of ovary (ovarian tissue freezing).1
Abbreviations and terms used
Assisted reproductive technology is a complex topic, and this document uses a number of technical terms. In the following discussion, where a technical term is used in the text for the first time it is given in bold type. You will also find its meaning explained in the glossary on page 14.
Where a term that has a commonly accepted abbreviation is used frequently, the first instance of the abbreviation will include the full spelling of the term and subsequent uses will rely on the abbreviation alone. Some of the most common abbreviations found in this document are:
ACART
Advisory Committee on Assisted Reproductive Technology
ECART
Ethics Committee on Assisted Reproductive Technology
HART Act 2004
Human Assisted Reproductive Technology Act 2004
IVF
in-vitro fertilisation.
2 Information about egg freezing
What is an egg?
At birth, the female reproductive gonad (ovary) contains all the eggs for a womans reproductive life. At any one time the majority of these eggs lie dormant, in a very immature state. During each menstrual cycle a few of these eggs start to develop as a result of hormonal changes in the woman, and in most cases one of these eggs will continue to develop and be released (ovulated) each month. By the time of ovulation the egg is over three times its original size and is primed ready for fertilisation it is now referred to as a mature egg. The drugs used in invitro fertilisation (IVF) treatments can allow more than one of these mature eggs to be produced in a single cycle.
Egg freezing as a procedure
Human embryo freezing has been used as an important part of fertility treatment for over 15years, and thousands of healthy babies have been born around the world from this technology. The same cannot be said for human egg freezing, which is still a relatively new procedure.
There are two basic ways for eggs to be frozen: controlled rate freezing and vitrification. These techniques are discussed in detail in Appendix1.
Egg freezing in New Zealand
In March 2005 the Advisory Group on Assisted Reproductive Technology (AGART)2 recommended that egg freezing be declared an established procedure as it alone offers a holding mechanism for women about to undergo cancer treatment. The group also recommended that the established procedure exclude the subsequent use of frozen eggs in treatment because the risks associated with this have not been able to be adequately assessed due to the novelty of the technique.
The current established procedure, which covers the freezing of eggs, does not set down the reasons for which freezing can be undertaken, and so women may freeze their eggs for any reason. However, reasons for egg freezing generally fall into one of three categories.
Medical reasons: women at risk of losing their fertility through early menopause, cancer treatment or other illness may freeze their eggs in the hope of later being able to use them to reproduce.
Spiritual, religious or ethical reasons: those undergoing fertility treatment may object to storing their embryos but may have no objection to storing their eggs and sperm.
Social reasons: for example, women who do not have a partner or who want to focus first on their career may wish to preserve their fertility by freezing some of their eggs for use at a later date.
Options for the use of frozen eggs
Once eggs have been frozen they might be thawed and used for research purposes or, if approved, for fertility treatment.
Use for fertility treatment
As we have seen, women who have had eggs removed and frozen to preserve their fertility could go on to use these previously frozen eggs in their own fertility treatment at a later date. Currently women may donate fresh eggs to other women whose own eggs are not viable. Donors may be personal donors who donate to friends or relatives, or they may be clinic-recruited donors who do not know the recipient. Potentially, the donation of frozen eggs to others could also be allowed.
Use for research purposes
Interim guidelines for the Ethics Committee on Assisted Reproductive Technology (ECART) regarding research on gametes and non-viable embryos were approved by the former Minister of Health, Hon Annette King, under section 83 of the HART Act 2004. The guidelines allow eggs, sperm and non-viable embryos to be donated for research purposes, provided ECART has given specific approval for each research proposal.
3 Assessment of known risks and benefits to health associated with the use of frozen eggs
This section summarises the known risks and benefits associated with the use of frozen eggs in fertility treatment. The information is discussed in more detail in Appendix 1.
Risks
Risks to the egg
The controlled-rate freezing procedure (using the cryoprotectants propanediol and sucrose) is similar to the process used for embryo freezing and has been used successfully in that context for over 15 years, resulting in the birth of thousands of healthy babies. However, this success has not been translated into egg freezing, mainly due to the vulnerable state of the mature egg, together with its large size and high water content.
The inability of an egg to respond to changes in the environment (both within the egg and its surroundings) during freezing and thawing has resulted in:
rupture of the cell membrane
rupture of components within the egg (cortical granules) that are involved in the fertilisation process
alterations to the fine filamentous structures that form the cytoskeleton just under the surface of the egg
damage to the spindle, a part of the egg that holds the chromosomes in place ready for fertilisation.
Any one of these kinds of damage reduces an eggs ability to be fertilised and could result in abnormal chromosome numbers after fertilisation.3 However, from the evidence available, ACART concludes that although egg freezing and thawing can cause some changes to the egg, the changes that occur are usually transient or able to be detected, allowing permanently affected eggs to be discarded.
Outcomes for children born from frozen eggs
There has been no genetic or developmental follow-up study of babies born from frozen eggs, possibly because so few babies have been born in any single fertility centre. Neither has there been any systematic reporting of pregnancy and birth data.
One study of 13 babies reported normal birthweight, normal karyotypes (chromosome numbers) and no malformations in any of the babies. In another study no chromosomal abnormalities were observed following amniocentesis sampling of five pregnancies. Another study reported 48healthy babies born, with no major malformations, following the double sucrose method. No information has been found on birth outcomes following the vitrification method (see Appendix 1).
The above studies report on only a small proportion of the total number of babies born from frozen eggs, which would currently be over 160.4 Future monitoring information on these births should more accurately assess the longer-term health outcomes for these babies.
There is a large amount of literature on the ongoing development of children born as a result of IVF. Although the data from that research shows a slight increase in congenital anomalies in children conceived as a result of IVF, there is no difference between children conceived with a fresh embryo transfer and children conceived as a result of the transfer of frozen embryos. It is also possible that the increased incidence of abnormalities is related to the genetic background of the individuals/couples involved in the treatment rather than the IVF procedure itself.
If the incidence is in fact related to the IVF procedure, then a similar profile for early childhood development could be expected in children born as a result of using frozen eggs. However, many more children need to be born and studied before any meaningful conclusions can be drawn.
ACART concludes that the evidence at this stage suggests that health outcomes for children born from the use of frozen eggs are similar to those for children born as a result of other IVF procedures. However, this is based on a limited number of studies, and further research is needed in this area.
Maternal health outcomes
No maternal complications have been reported following the use of frozen eggs, although miscarriage does occur. Whether the incidence is increased relative to IVF is difficult to tell at present. One group using the altered salt and low sucrose method reported that three out of six pregnancies were lost before 12weeks gestation. Another group reported a level of 20 percent loss using the initial low sucrose method and three losses from 18 pregnancies with the triple sucrose method. Although these latter miscarriage rates are not significantly different from those associated with embryo freezing, the numbers are too low to make a meaningful comparison at this stage.
Benefits
Embryo freezing and the use of frozen embryos in fertility treatment have been well established for many years and are relatively successful techniques. Although it is unlikely that the results for egg freezing will surpass those for embryo freezing in the near future, there are situations where the freezing and subsequent use of frozen eggs is preferable to embryo freezing, including:
where embryos cannot be formed due to there being no sperm for fertilisation
in the case of young single women with malignant conditions or related treatments that threaten their fertility
where the individual/couple undergoing fertility treatment objects to creating and storing multiple embryos.
These benefits are only possible if the subsequent use of frozen eggs is permitted.
Monitoring
The lack of evidence discussed above highlights the need for data collection on the outcomes for children born in New Zealand as a result of assisted reproductive procedures. ACART is currently investigating the best ways to collect this data.
For the use of frozen eggs, ACART considers that the following information would be necessary to monitor the procedure adequately:
freezing method used
original reason for freezing
fertilisation method used
number of clinical pregnancies and deliveries
frequency of multiple births
birthweight
gestational age
gender
age of mother at birth
frequency of congenital abnormalities
perinatal mortality (stillbirths and neonatal mortality).
1. Given these risks and benefits, what is your opinion on ACARTs proposed advice to the Minister of Health? Please give reasons for your views.(See chapter 3 for a discussion of risks and benefits, and chapter 6 for the proposed advice.)
2. What is your view on the information that ACART suggests should be collected to monitor the use of frozen eggs in fertility treatment?
4 Acceptability of the risks associated with the use of frozen eggs
ACART has developed a framework to help assess the acceptability of risks associated with a particular procedure or treatment, and this has been used here to consider the acceptability of the risks associated with the use of frozen eggs in fertility treatment. Note that the risks associated with the collection and freezing of eggs are not considered because the freezing of eggs is an established procedure and is outside the scope of this document. This section summarises ACARTs view on the acceptability of the risks associated with the use of frozen eggs. The full analysis of the risks associated with the use of frozen eggs is set out in Appendix2.
There are very few known health risks associated solely with the use of frozen eggs, and ACARTs analysis indicates that the known risks fall within a level of risk that is acceptable in New Zealand, for the following reasons.
For some women (particularly those undergoing treatment for cancer), egg freezing and the subsequent use of those frozen eggs will be the only option available to them to have genetically related children.
The miscarriage risk is similar to the miscarriage risk associated with the use of frozen embryos (though numbers are too small to make a meaningful comparison at this stage).
There has been a reasonable uptake of the technology and approximately 1605 births in other countries.
No country has banned egg freezing, although the Hungarian Ministry of Health is considering a moratorium pending further research.
There are few ethical issues associated with the use of frozen eggs, and ACART considers these issues are best dealt with in discussions between the clinician and the patient.
ACART considers the use of frozen eggs to be consistent with the purposes and principles of the HART Act 2004.
There is, however, a lack of data on outcomes for children born from eggs that have previously been frozen. Implementation of a monitoring regime will, therefore, be an important part of ACARTs recommendations to the Minister.
5 Ethical Analysis
Overall, ACART considers that there are few ethical issues associated with the use of frozen eggs. This section discusses these issues.
Informed consent
The HART Act 2004 requires that no assisted reproductive procedure be performed on an individual unless the individual has made an informed choice and given informed consent.
Fertility services and associated health professionals are subject to the Code of Health and Disability Services Consumers Rights 1996, which confers 10 rights on consumers of health and disability services, including the right to make an informed choice and give informed consent.
In addition, more detailed requirements for informed consent, specific to assisted reproduction, are set out in the Fertility Services Standard. This standard sets out the regulations under which fertility professionals are required to operate. The standard requires that:
full information be provided, both in writing and verbally, on all aspects of the use of frozen eggs, including:
an acknowledgement that the use of frozen eggs may be unsuccessful
suggestions for any alternative options
details of the components of the procedure
a list of all risks and possible side effects or complications
an explanation of all terminology
information be provided about the experimental nature of using frozen eggs and the lack of evidence about the health of children born from frozen eggs
adequate time and opportunity be provided for patients to discuss their treatment with competent staff.
Posthumous use of frozen eggs
The technology of egg freezing potentially allows for the future use of eggs from a woman who has died since having her eggs frozen. This issue is especially pertinent if egg freezing is used to preserve the fertility of cancer patients who later die. Under the Reproductive Technology Accreditation Committees (RTACs) code of practice, fertility clinics consent forms to freeze eggs must state what is to be done with those eggs if the consenting person dies or becomes incapable of varying their consent. The Fertility Services Standard also requires providers to have procedures in place for dealing with situations where the consenting person dies or becomes incapable of varying their consent. ACART considers that the use of frozen eggs after the death of a woman is covered by these requirements.
Donating frozen eggs for treatment purposes
At present, egg donation is an established procedure under the HART Act 2004. The established procedure does not specify whether the donated eggs must be fresh or frozen.
ACART considers that the use of frozen eggs should not be restricted to a womans own use. Provided that the women receiving donated frozen eggs are informed of the risks associated with their use, and of the procedures relative novelty as a form of treatment, ACART sees no reason to prohibit the donation of frozen eggs for use in fertility treatment. At present, fresh eggs are preferred, but occasionally it may be necessary to use frozen eggs for egg donation (for example, to make it easier to synchronise with the recipients cycle).
M o r i p e r s p e c t i v e s
T h e H A R T A c t r e q u i r e s t h a t e v e r y o n e e x e r c i s i n g p o w e r s o r p e r f o r m i n g f u n c t i o n s u n d e r t h i s A c t m u s t b e g u i d e d b y i t s p r i n c i p l e s , i n c l u d i n g t h e p r i n c i p l e t h a t t h e n e e d s , v a l u e s , a n d b e l i e f s o f M o r i s h o u l d b e c o n s i d e r e d a n d t r e a t e d w i t h r e s p e c t .
M o r i p e r s p e c t i v e s a r e d i v e r s e a n d a r e l i k e l y t o d i f f e r b o t h b e t w e e n a n d w i t h i n i w i , h a p k a n d w h n a u . A l t h o u g h i t i s u n l i k e l y t h e r e w i l l b e a s i n g l e M o r i v i e w o n t h e u s e o f f r o z e n e g g s i n f e r t i l i t y t r e a t m e n t , t h e r e m a y b e c o m m o n c o n c e r n s t h a t a r i s e f r o m w i t h i n t e a o M o r i ( t h e M o r i w o r l d v i e w ) . T h i s s e c t i o n o u t l i n e s s o m e o f t h e f u n d a m e n t a l v a l u e s a n d b e l i e f s o f M o r i t h a t a r e r e l e v a n t t o f e r t i l i t y t r e a t m e n t .
K n o w l e d g e a n d p r o t e c t i o n o f w h a k a p a p a i s a k e y c o n c e r n t h a t h a s b e e n e x p r e s s e d t o A C A R T d u e t o t h e p o t e n t i a l i m p l i c a t i o n s f o r e n t i t l e m e n t t o r e s o u r c e s , s u c h a s l a n d , a n d f o r w i d e r w h n a u r e l a t i o n s h i p s . S o m e M o r i a r e c o n c e r n e d t h a t w h a k a p a p a w o u l d b e d i s r u p t e d t h r o u g h t h e u s e o f s o m e a s s i s t e d r e p r o d u c t i v e p r o c e d u r e s . T h e H A R T A c t r e q u i r e s t h a t i n f o r m a t i o n a b o u t d o n o r s b e k e p t b y p r o v i d e r s a n d t h e R e g i s t r a r - G e n e r a l o f B i r t h s , D e a t h s a n d M a r r i a g e s . T h e A c t s p e c i f i e s t h a t e t h n i c i t y a n d a n y r e l e v a n t c u l t u r a l a f f i l i a t i o n m u s t b e r e c o r d e d a n d , i n t h e c a s e o f M o r i d o n o r s , t h e d o n o r s w h n a u , h a p k a n d i w i a f f i l i a t i o n s .
S o m e M o r i h a v e r a i s e d c o n c e r n s o v e r w h o h a s t h e m a n a t o m a k e d e c i s i o n s a b o u t t h e u s e o f a s s i s t e d r e p r o d u c t i v e t e c h n o l o g y . R e c o g n i t i o n o f m a n a t h r o u g h t h e p o t e n t i a l i n v o l v e m e n t o f w h n a u i n d e c i s i o n - m a k i n g i s i m p o r t a n t b e c a u s e i t :
g i v e s w h n a u a n o p p o r t u n i t y t o e x p l o r e w a y s t o a d d r e s s i n f e r t i l i t y ( a n e x p r e s s i o n o f w h a n a u n g a t a n g a )
p r o v i d e s a s p a c e i n w h i c h t o d i s c u s s t h e c u l t u r a l i m p l i c a t i o n s o f a s s i s t e d r e p r o d u c t i o n , i n c l u d i n g r i g h t s o f a c k n o w l e d g e m e n t , a c c e s s t o i n f o r m a t i o n b e y o n d t h a t s e t o u t i n t h e H A R T A c t , t h e u s e o f s u r n a m e s , a n d c l a i m s t o r e s o u r c e s t o w h i c h t h e d o n o r s f a m i l y m a y b e b e n e f i c i a r i e s . 6
T h e F e r t i l i t y S e r v i c e s S t a n d a r d p r o v i d e s f o r t h e i n v o l v e m e n t o f w h n a u i n f e r t i l i t y t r e a t m e n t .
I n t h e c o n t e x t o f a s s i s t e d reproduction, tino rangatiratanga involves the right to self-determination at both an individual and collective level, and the ability to express kaitiakitanga (guardianship). Frozen eggs remain under the mana of the woman from whom they have been taken and, if subsequently donated, this remains true until they enter the whare tangata (womb). In this case the responsibility to protect whakapapa resides with the Registrar-General of Births, Deaths and Marriages and wh n a u , h a p k a n d i w i .
A C A R T h o p e s t h a t t h i s d i s c u s s i o n w i l l e n c o u r a g e M o r i t o c o n s i d e r t i k a n g a ( p r o t o c o l s ) t h a t a r e r e l e v a n t t o a s s i s t e d r e p r o d u c t i o n , a n d a p p r o p r i a t e w a y s t o r e s p e c t t h e v a l u e s a n d b e l i e f s o f M o r i i n t h e d e v e l o p m e n t o f p o l i c y a n d t h e p r o v ision of services to treat infertility.
Human rights issues
In New Zealand the Human Rights Act 1993 prohibits discrimination on the basis of a variety of factors, including gender, age and religious belief.
Gender
For several decades men have been able to preserve their fertility, for whatever reason, by freezing their sperm. They have then been able to use their frozen sperm without specific approval from an ethics committee. It could be argued that women should also have access to this technology without constraint.
Age
The technology of egg freezing, thawing and subsequent use may allow women to freeze their eggs and use them to bear children when they are of an advanced age or post-menopausal. This may, however, be only theoretical as eggs may only be stored for a maximum of 10years, unless a specific extension is granted by ECART, based on guidelines that are to be developed by ACART. Given the upper age at which it would be sensible to collect and freeze eggs for reproductive use, the 10-year limit will restrict the age at which most women could use frozen eggs to reproduce.
Religious belief
Contemporary New Zealand is home to a variety of religions. For some the use of any assisted reproductive treatment may be unacceptable. Others agree with some forms of treatment, but find embryo freezing and the dilemma of having to decide what to do with embryos that are surplus to reproductive requirements unacceptable. The use of frozen eggs would provide a more ethically acceptable alternative to the use of frozen embryos for people who have these concerns.
Equity
Another issue relevant to the use of frozen eggs concerns access to the technology. The freezing and future use of frozen eggs is likely to include paying for the following services:
ovarian stimulation
egg collection
egg freezing
storage of eggs (annual fee)
use of eggs in treatment (up to two cycles of IVF are now publicly funded)
other associated costs.
It is likely that these costs will restrict who is able to access this technology. In addition, it is probable that the above services will only be available in larger centres around the country, limiting access to the technology for those who live in smaller centres in New Zealand.
Use of eggs for social reasons
A woman might want to freeze and use her eggs to preserve her fertility for personal reasons (for example, where she does not have a current partner or lacks the material resources to support a child at present). Specifically freezing and using frozen eggs for personal reasons raises questions about reproductive autonomy and the rights of the individual versus community acceptability of technologies.
ACART considers that current evidence would not support a womans belief that she would be preserving her fertility, given that the birth rate from the use of frozen eggs remains relatively low. ACART considers that the freezing of eggs is at best a backstop measure for those who are at risk of losing their fertility altogether, and that it would be unwise for women to rely on egg freezing for social reasons. Decisions on egg freezing are, however, best clarified between the clinician and the patient to ensure that a woman (or couple) is given full information on the procedure and is able to make an informed choice.
3. Has ACART identified all the ethical issues relevant to the use of frozen eggs in fertility treatment? Do any of these issues affect ACARTs proposed advice that the use of frozen eggs should be allowed in fertility treatment? If so, how?
6 Conclusion: Proposed advice to the Minister
ACART proposes to recommend to the Minister that the use of frozen eggs become an established procedure for:
individual treatment purposes (use of frozen eggs in fertility treatment by the woman who originally stored them)
donation for treatment purposes (use of frozen eggs by other women in fertility treatment)
donation for use in research.
ACARTs reasons for its recommendations are as follows.
The collection and freezing of eggs is currently an established procedure, and so there would have to be strong reasons to prevent women from subsequently using their frozen eggs.
Although it is still a relatively new technique, the available evidence suggests that the risks to the resulting child associated with the use of frozen eggs are no greater than those associated with the use of frozen embryos or IVF generally, given that damaged eggs will be identified and discarded or will not fertilise.
For some women, particularly those undergoing cancer treatment, egg freezing and subsequent use will be the only option available to preserve their fertility.
Egg freezing and subsequent use also offer an alternative to those who, for religious or spiritual reasons, find the freezing of embryos unacceptable.
There appear to be few ethical issues associated with the use of frozen eggs, and ACART considers that these issues can be managed in discussions between clinician and patient.
Although it is preferable to use donated fresh eggs because of their greater rate of success, allowing the use of frozen donated eggs means that the cycles (of both the donor and the receiver) can be better synchronised where necessary.
Allowing the use of frozen eggs puts women on an equal footing with men, who are free to use their frozen sperm for fertility treatment.
If the Minister approves the use of frozen eggs as an established procedure, it will be ACARTs responsibility to collect information to monitor the health outcomes of children born as a result of the use of frozen eggs.
4. Should the use of frozen eggs in fertility treatment become an established procedure? If not, why, and how should the use of frozen eggs be regulated?
5. Should the use of frozen eggs in fertility treatment be limited to the individuals the eggs came from, or should frozen eggs be able to be donated to others for use in fertility treatment?
6. Should frozen eggs be able to be donated for research purposes?
Glossary
Advisory Committee on Assisted Reproductive Technology (ACART)The advisory committee established under New Zealands Human Assisted Reproductive Technology Act 2004.Advisory Group on Assisted Reproductive Technology (AGART)The group convened in June 2004 to provide the Director-General of Health with an assessment of the risks and benefits associated with assisted reproductive technologies. The groups work resulted in the list of established procedures.AmniocentesisThe sampling of the amniotic fluid (the fluid that encloses an embryo) by inserting a hollow needle into the fluid to determine the condition of the embryo.Assisted reproductive procedureThe Human Assisted Reproductive Technology Act 2004 defines an assisted reproductive procedure as a procedure performed for the purpose of assisting human reproduction that involves:
the creation of an in-vitro human embryo, or
the storage, manipulation or use of an in-vitro human gamete or an in-vitro human embryo, or
the use of cells derived from an in-vitro human embryo, or
the implantation into a human being of human gametes or human embryos.CryopreservationThe freezing and storage of tissues and cells at extremely low temperatures.CryoprotectantA solution that will crystallise in a controlled way at a subzero temperature.CytoskeletonThe series of protein skeletal elements found in a living cell that gives shape and coherence to the cell.EmbryoThis includes a zygote and a cell or group of cells that has the capacity to develop into an individual, but does not include stem cells derived from an embryo.Established procedureA procedure that is declared established under section 6 of the Human Assisted Reproductive Technology Act 2004 and therefore does not require approval from ECART.Ethics Committee on Assisted Reproductive Technology (ECART)The ethics committee established under New Zealands Human Assisted Reproductive Technology Act 2004.Fertility Services StandardA standard issued under the Health and Disability Services (Safety) Act 2001 that sets out the safety and quality measures that all fertility services provided by New Zealand fertility clinics must meet. This standard will come into force in 2009.GameteAn egg or sperm, whether mature or not, or any other cell (whether naturally occurring or artificially formed or modified) that (i) contains only one copy of all or most chromosomes and (ii) is capable of being used for reproductive purposes.Human Assisted Reproductive Technology Act 2004 (HART Act 2004)An act to secure the benefits of, and regulate, assisted reproductive technology and human reproductive research.Human reproductive researchResearch that uses or creates a human gamete, a human embryo or a hybrid embryo.Informed consentA persons voluntary agreement, based on adequate knowledge and understanding of relevant information, to participate in research or to undergo a diagnostic, therapeutic or preventive procedure.In-vitro fertilisation (IVF)The uniting of egg and sperm outside the body (in the laboratory).KaitiakitangaGuardianship ManaA concept that implies authority, influence and prestige, as well as the recognition of these qualities.National Ethics Committee on Assisted Human Reproduction (NECAHR)An ethical review and policy body that was established in 1993 to manage some aspects of assisted reproductive technologies before the passing of the Human Assisted Reproductive Technology Act 2004.OvaryThe egg-producing reproductive organ found in females.OvulationThe process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an egg that participates in reproduction.Te ao M o r i M o r i w o r l d v i e w . T i k a n g a P r o t o c o l s o r t h e r i g h t w a y s o f d e a l i n g w i t h i s s u e s t h a t a r i s e i n r e l a t i o n t o a t o p i c . T i n o r a n g a t i r a t a n g a T h e r i g h t t o s e l f - d e t e r m i n a t i o n a t b o t h a n i n d i v i d u a l a n d a c o l l e c t i v e l e v e l . W h a k a p a p a T h e g e n e a l o g i c a l d e s c e n t of all living things from the gods to the present time.WhanaungatangaThe obligation of care and support among relatives.Whare tangataWomb.ZygoteThe product of the fusion of an egg and a sperm. It contains two copies of each chromosome, one from each parent. The zygote develops into an embryo.
Appendix 1: Report on Egg Freezing for ACART
(February 2008, prepared by Dr Debra Gook, Senior Research Fellow, Reproductive Services, Royal Womens Hospital and Melbourne IVF, Melbourne, Australia)
An overview of egg freezing
Why cryopreserve human eggs?
Although human embryo cryopreservation (freezing) has been used as an important adjunct to fertility treatment for over 15years and thousands of normal babies have been born around the world from this technology, the same cannot be said for human egg (oocyte) freezing. The potential clinical benefits of oocyte cryopreservation include (but are not restricted to) preservation of fertility options for women of reproductive age who are at risk of losing their ability to produce eggs as a result of toxic anticancer treatments but have no partner and are, therefore, unable to benefit from routine embryo freezing procedures ADDIN EN.CITE Gook199917950Gook, D. A.Edgar, D. H.1999Cryopreservation of the human female gamete: current and future issuesHum Reprod14122938-40.Cryopreservation/*methods/*trendsFemaleHuman*Oocytes[1].
Although three babies were born from egg freezing in the 1980s, the technology was never systematically used for clinical material until the late 1990s. The more vulnerable state of the egg and the poor initial success rate were the major contributors to the lack of clinical application. Many of the concerns regarding egg freezing were based on animal studies, but subsequent evidence from research using human eggs has indicated that these may be unfounded and relate specifically to species difference. These human studies together with a number of recent clinical egg freezing programs suggest that the technology is a viable option for appropriate patients (recent review ADDIN EN.CITE Gook200720790178461051362007November-DecemberHuman oocyte cryopreservation591-605Reproductive Services/Melbourne IVF, Royal Women's Hospital, 132 Grattan Street, Carlton, Victoria 3053, Australia.Gook, D. A.Edgar, D. H.Hum Reprod Updatehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17846105[2]).
What is an egg?
At birth, the female reproductive gonad (ovary) contains the total complement of eggs for the female reproductive life. At any point during reproductive life, the majority of these eggs lie dormant in a very immature state. Each menstrual cycle, a few of these eggs start to develop as a result of hormonal changes in the woman and, in most cases, one of these developing eggs will continue to develop and be released (ovulated) each month. By the time of ovulation the egg is over three times its original size and is primed ready for fertilisation this is referred to as a mature egg. The drugs used in IVF treatments can allow more than one of these mature eggs to be produced in a single cycle. The mature egg, prior to being fertilised, is in a dynamic state in which it is potentially vulnerable to any changes in its environment. Exposure to any inappropriate environment may render the mature egg unable to proceed through the processes of fertilisation and subsequent division into an embryo consisting of multiple cells and, therefore, prevent a resultant pregnancy. If not applied in an appropriate way, egg cryopreservation may have this effect.
Egg freezing
Generally eggs are frozen at two of the above developmental stages at the very immature stage in pieces of ovary and at the mature stage following collection for IVF. The freezing of eggs within pieces of the ovary is a new technology that has been developed for storing reproductive potential in young women with malignant disease who are often rendered menopausal following chemotherapy and radiotherapy ADDIN EN.CITE Gosden1997300Gosden, R.GRutherford, A.JNorfolk, D.R1997Ovarian banking for cancer patients. Tranmission of malignant cells in ovarian grafts.Human Reproduction123403-405cryopreservation, follicle,human,cancer,ovaryGook200017630Gook, D. A.Edgar, D. H.Stern, C.2000The effects of cryopreservation regimens on the morphology of human ovarian tissueMol Cell Endocrinol1691-299-103.Cell Survival/drug effectsCryopreservation/*methods/standardsDesiccation/methodsDimethyl Sulfoxide/pharmacologyFemaleGranulosa Cells/cytologyHumanOocytes/cytologyOvary/*cytologyPregnancyPropylene Glycol/pharmacologyStromal Cells/cytologySucrose/pharmacologyTemperatureOktay20008970Oktay, KKarlikaya, GAydin, BA2000Ovarian transplantation: now a reality?Mol Cell Endocrin(in press)Radford200117510Orthotopic reimplantation of cryopreserved ovarian cortical strips after high-dose chemotherapy for Hodgkin's lymphomaRadford, J. A.Lieberman, B. A.Brison, D. R.Smith, A. R.Critchlow, J. D.Russell, S. A.Watson, A. J.Clayton, J. A.Harris, M.Gosden, R. G.Shalet, S. M.Lancet200135792631172-5.[36]. Although the freezing of the pieces of ovary is promising, very little information is available regarding the clinical potential of this technology ADDIN EN.CITE Meirow200117830The effects of radiotherapy and chemotherapy on female reproductionMeirow, D.Nugent, D.AdolescenceAdultAge FactorsChildDrug Therapy/adverse effectsFemaleHumanInfertility/*etiologyNeoplasms/*complications/drug therapy/radiotherapyOvary/*drug effects/pathology/*radiation effectsRadiotherapy/adverse effectsHum Reprod Update200176535-43.Oktay2004186701503102636394122004Mar 13Embryo development after heterotopic transplantation of cryopreserved ovarian tissue837-40Center for Reproductive Medicine and Infertility, Joan and Sanford I Weill Medical College of Cornell University, 505 East 70th Street, HT-340, New York, NY 10021, USA. kuo9001@med.cornell.eduOktay, K.Buyuk, E.Veeck, L.Zaninovic, N.Xu, K.Takeuchi, T.Opsahl, M.Rosenwaks, Z.LancetAbdominal Wall/surgeryAdolescentAntineoplastic Agents/adverse effectsBone Marrow TransplantationBreast Neoplasms/drug therapy/surgery*CryopreservationEmbryo and Fetal Development/*physiologyEstradiol/bloodFemaleFollicle Stimulating Hormone/bloodHumanInfertility, Female/blood/chemically induced/etiologyMaleMenopause, Premature/drug effects/physiologyOocytes/growth & development/physiologyOvarian Follicle/growth & developmentOvary/physiology/surgery/*transplantationSperm Injections, IntracytoplasmicSupport, Non-U.S. Gov't*Transplantation, Heterotopichttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15031026Schmidt200418790Schmidt, K.L.T.Andersen, C.Y.Starup, J.Loft, A.Byskov, A.G.Andersen, A.N.2004Orthotopic autotransplantation of cryopreserved ovarian tissue to a women cured of cancer- follicular growth, steroid production and oocyte retrieval.Reprod. BioMed. Online84448-453Gook200519030154719282012005JanDiagnostic assessment of the developmental potential of human cryopreserved ovarian tissue from multiple patients using xenografting72-8Reproductive Services, Royal Women's Hospital, 132 Grattan Street, Carlton, Victoria 3053, Melbourne IVF, 320 Victoria Parade, East Melbourne, Victoria 3002, Australia. debra.gook@rwh.org.auGook, D. A.Edgar, D. H.Borg, J.Archer, J.McBain, J. C.Hum ReprodAdolescentAdultAnimalsAntineoplastic Agents/adverse effects*CryopreservationFemaleHumansIn VitroMiceMice, SCIDNeoplasms/drug therapyOvarian Follicle/physiology*Ovary/drug effects/growth & development/physiology/transplantation*Tissue PreservationTransplantation, Heterologoushttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15471928Dolmans200519080158207978342005AprEfficacy of in vitro fertilization after chemotherapy897-901Department of Gynecology, Universite Catholique de Louvain, Cliniques Universitaires St. Luc, Avenue Hippocrate 10, 1200 Brussels, Belgium.Dolmans, M. M.Demylle, D.Martinez-Madrid, B.Donnez, J.Fertil SterilAdultAntineoplastic Agents/*adverse effects*Cryopreservation*Embryo TransferFemaleFertilization in Vitro/*methodsHumansInfertility, Female/*etiologyNeoplasms/*drug therapyOvary/cytologyOvulation InductionResearch Support, Non-U.S. Gov'tRetrospective Studieshttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15820797[711]. Two births have been reported from this technology recently ADDIN EN.CITE Donnez2004188801548821536494432004Oct 16Livebirth after orthotopic transplantation of cryopreserved ovarian tissue1405-10Department of Gynaecology, Cliniques Universitaires St Luc, Universite Catholique de Louvain, Avenue Hippocrate 10, B-1200, Brussels, Belgium. donnez@gyne.ucl.ac.beDonnez, J.Dolmans, M. M.Demylle, D.Jadoul, P.Pirard, C.Squifflet, J.Martinez-Madrid, B.van Langendonckt, A.Lancethttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15488215Meirow2005191001598302035332005Jul 21Pregnancy after transplantation of cryopreserved ovarian tissue in a patient with ovarian failure after chemotherapy318-21Meirow, D.Levron, J.Eldar-Geva, T.Hardan, I.Fridman, E.Zalel, Y.Schiff, E.Dor, J.N Engl J MedAdult*CryopreservationFemaleFertilization in VitroHumansLymphoma, Non-Hodgkin/drug therapyOvarian Failure, Premature/chemically inducedOvary/*transplantation*PregnancyTransplantation, Autologoushttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15983020[12, 13]. The remainder of this report will concentrate on the freezing of mature eggs.
There are two basic processes by which cells can be frozen controlled rate techniques or vitrification.
Controlled rate freezing
To successfully achieve survival after controlled rate freezing, water within the egg cell must be removed and replaced with a solution that will crystallise in a controlled fashion at a subzero temperature. This solution is referred to as a cryoprotectant.
To assist with the removal of water from the egg, a second cryoprotectant (sucrose) is also added, but this does not enter the egg. After sufficient time for displacement of the water, the egg is placed in a sealed plastic straw. The temperature is slowly reduced to the crystallisation temperature and then further reduced at an even slower rate to 196(C. The eggs remain at this temperature in liquid nitrogen storage tanks until required. To thaw the eggs, the procedure is essentially reversed, bringing the egg quickly back to body temperature and replacing the cryoprotectant inside the egg with water.
Vitrification
In this case, the egg is exposed to a combination of very concentrated cryoprotectants, often for only 30 seconds, and then the temperature is dropped very quickly to 196(C.
The major difference in this procedure compared to controlled rate freezing is that there is no crystallisation. Due to the high concentration of the cryoprotectants and the ultra-rapid rate at which the temperature is reduced, the surrounding solution and that inside the egg never crystallise and form a glass-like (vitrified) state.
Again, to thaw the egg, a reverse procedure is applied. It appears, from experience with the vitrification of other types of cells that minor variations in the time of exposure to the cryoprotectant (sometimes as little as a few seconds) can result in damage. Previously, vitrification has been used mainly for animal embryos; however, more recently it has been applied to clinical egg and embryo storage.
Current status of the procedure
Has egg freezing been banned?
Unlike embryo freezing, which has been banned in Germany for a number of years and in Italy since 2004 ADDIN EN.CITE Ragni200519780158175862082005AugThe 2004 Italian legislation regulating assisted reproduction technology: a multicentre survey on the results of IVF cycles2224-8Infertility Unit, 'Policlinico--L. Mangiagalli' Hospital, Milano, Reproductive Medicine Unit, ANDROS Day Surgery, Palermo (Palermo I), Italy. g.ragni@icp.mi.itRagni, G.Allegra, A.Anserini, P.Causio, F.Ferraretti, A. P.Greco, E.Palermo, R.Somigliana, E.Hum ReprodAdult*CryopreservationData CollectionEmbryo Transfer/statistics & numerical dataFemaleFertilization in Vitro/*legislation & jurisprudence/statistics & numericaldataHumansIncidenceItaly/epidemiologyOocytesPregnancyPregnancy RatePregnancy, Multiple/statistics & numerical dataSperm Injections, Intracytoplasmic/*legislation & jurisprudence/statistics& numerical datahttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15817586[14], based on ethical reasons, there appears to be no specific legislation in any country banning egg freezing at present.
Is approval required for egg freezing?
A survey of IVF groups in a number of major countries (Australia, United States, United Kingdom, Canada, France, Sweden, Finland, Italy) indicated that there is also no requirement for specific approval of egg freezing.
Although there is a general consensus that this technology should be available for young women with cancer, there is controversy relating to its use for extending female fertility. The Practice Committees of the Society for Assisted Reproductive Technology (USA) and the American Society for Reproductive Medicine were of the opinion that oocyte cryopreservation is an experimental procedure that should not be offered or marketed as a means to defer reproductive aging. They further stated that oocyte cryopreservation is not an established medical treatment. However, this was subsequently qualified when they suggested a number of guidelines for providing information to women who may wish to insure against declining fertility. They also suggested that institutional board approval be required.
Controversy about banning
Although there are no bans on egg freezing at present, a recent article ADDIN EN.CITE Konc200719790172073241412007JanDoes oocyte cryopreservation have a future in Hungary?11-3Infertility and IVF Centre of Buda, Saint Janos Hospital, Budapest 1125, Hungary.Konc, J.Kanyo, K.Cseh, S.Reprod Biomed Onlinehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17207324[15] indicated that the Hungarian Ministry of Health is currently working on a proposal that intends to ban egg freezing in Hungary temporarily. The standpoint taken is that the safety of the technology has not been proven and that there is a high risk to the genetic material within the egg, which translates to a significantly increased risk to the offspring. The Ministry is requesting further animal experimentation to clarify the probability of permanent lesions to the spindle and alterations of the genetic material. They also believe that, at present, suspension is justified due to the low efficiency of the procedure, which has reached the level required for clinical adoption.
Information provided in the subsequent sections of this report will show that many of the animal studies do not correlate with the conditions for human egg freezing and that species differences in the egg have a major impact on the results obtained for egg freezing. It is the authors opinion that more weight should be given to studies using the exact material that would be frozen in the clinical situation, that is, the human mature egg, and not to animal studies. The report will also show that, at present, the efficiency of egg freezing with new developments is approaching that observed for other assisted reproductive technologies.
Number of patients
In the mid 1980s when egg freezing was first introduced as a clinical procedure, only four patients were reported, and these were all patients achieving a pregnancy ADDIN EN.CITE Van Uem1987910Van Uem,J.F.H.M.Siebzehnrubl,E.R.Schuh,B.Koch,R.Trotnow,S.Lang,N.1987Birth after cryopreservation of unfertilised oocytes.Lanceti752-753Chen1986720Chen,C1986Pregnancy after human oocyte cryopreservation.Lanceti884-886Al-Hasani19871540Al-Hasani, S.Diedrich, K.van der Ven, H.Reinecke, A.Hartje, M.Krebs, D.1987Cryopreservation of human oocytesHum Reprod28695-700Comparative StudyCryoprotective AgentsDimethyl Sulfoxide/*pharmacologyFemaleFertilization in Vitro/*methodsFreezingHuman*Oocytes/drug effectsPropylene Glycols/*pharmacologyTissue Preservation/*methods[1618]. Egg freezing resurfaced some 10 years later, following the report of a baby born ADDIN EN.CITE Porcu19974990Porcu, E.Fabbri, R.Seracchioli, R.Ciotti, P. M.Magrini, O.Flamigni, C.1997Birth of a healthy female after intracytoplasmic sperm injection of cryopreserved human oocytesFertil Steril684724-6AdultCase Report*Cryopreservation*Cytoplasm*DeliveryEmbryo TransferFemaleFertilizationHumanMaleMicroinjections*MicromanipulationOocytes/*physiologyPregnancyReference Values*SpermatozoaSupport, Non-U.S. Gov't[19] using a new procedure; the procedure currently used. Again, the number of patients for which the procedure had been used were small generally pilot studies or case reports of successful pregnancies (56 patients).
Although this trend has continued for the use of egg freezing in a small population of specific patients, for example, couples in which no sperm was obtained during IVF treatment, the change to the law in Italy suggests that in Italian clinics that use egg freezing to overcome the limitation of creating only three embryos, the majority of IVF patient would have eggs frozen in every cycle. At least in Italy this will translate over the next few years into an exponential increase in the number of patients using egg freezing. The national Italian data for 2005, presented at the recent Second World Congress on Human Oocyte Cryopreservation 2007, reported that only 12 percent of patients had frozen eggs, which translates to 12,689 eggs.
In the literature at present, there are reports of egg freezing from clinics in 15countries (United States, Australia, Canada, Spain, Germany, Hungary, Czech Republic, Brazil, Argentina, Colombia, China, Taiwan, Korea, Japan and Italy). From these reports, it can be seen that over 2,600 patients have frozen more than 16,818 eggs ADDIN EN.CITE Serafini19958620Serafini,PTran, CTan,TNelson,JBatzofin,J1995Cryopreservation of human oocytes-a clinical trial.Journal of Assisted Reproduction and Genetics1236S Abst. 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Abst P-55, 14th Annual ESHRE Meetingcryopreservation,oocyte,human,pregnancyVidali199820660Vidali, A.Dani, G.Antinori, M.Cerusico, F.Versaci, C.Antinori, S.1998Oocyte cryopreservation is a viable alternative option for patients who refuse embryo freezingFertility and Sterility70suppl 1S138Young19986300Young, E.Kenny, A.Puigdomenech, E.Van Thillo, G.Tiveron, M.Piazza, A.Triplet pregnancy after intracytoplasmic sperm injection of cryopreserved oocytes: case reportAdultCase Report*CryopreservationCytoplasmFemaleHumanInfertility, Female/*therapyMaleMicroinjections*OocytesPregnancy*Pregnancy, Multiple*Sperm-Ovum Interactions*TripletsFertil Steril1998702360-1Polak de Fried19984980Polak de Fried,ENotrica,JRubinstein,MMarazzi,A1998Oocyte cryopreservation program: Removal vs non removal of cumulus corona complexFertility and Sterility70, Suppl. 1Suppl. 1S148. 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K.Kim, T. J.Park, S. E.Hong, S. W.Ko, J. J.Chung, H. M.Cha, K. Y.Fertil SterilAdultCryopreservation/*methods*Embryo TransferFemale*Fertilization in VitroHumanInfant, Newborn*OocytesPregnancySperm Injections, IntracytoplasmicSupport, Non-U.S. Gov'thttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=12798878Kuwayama200519300161766681132005SepHighly efficient vitrification method for cryopreservation of human oocytes300-8Kato Ladies' Clinic, Tokyo, Japan. masaabc@bokkoame.ne.jpKuwayama, M.Vajta, G.Kato, O.Leibo, S. 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Outcome
For all assisted reproductive technologies, the ultimate outcome is measured as the number of live births achieved. In the above studies, 220 babies were reported from the thawing of 16,818 eggs, which equates to 1.3 babies for every 100 oocytes thawed. Similarly, the Italian data for 2005 (some of which would have been also reported in the above publications) resulted in at least 133 babies born from the thawing of 12,689 eggs (1.0 baby/100 eggs). In comparison, in Victoria, Australia, for the year 2004, from 56,986 fresh eggs collected, 1271 babies were born following transfer of fresh embryos (2.2babies/100 eggs). The additional contribution of frozen embryos increased the figure to three babies per 100 eggs collected (data for IVF procedures collected by the State Government of Victoria, Australia).
One confounding factor in reporting the total number of births from egg freezing is that, in many of the above reports, the final outcome was only measured as foetal heart detection (of which 507 have been reported), and therefore the above calculation of 1.3/100 is an underestimation of the outcome. Theoretically, assuming a 20 percent miscarriage rate, which many of the controlled rate freezing procedure papers report, the reduction from foetal heart detection to birth (406) would result in 2.4babies/100 eggs, which is approaching the result for frozen embryos.
Other confounding factors are that the data has been generated using two extremely different procedures; controlled rate freezing and vitrification, with a number of modifications applied to both, and that miscarriage rates may be higher with some procedures. A more accurate assessment of the outcomes and efficiency of each of the procedures will be described further on in this report.
Risk of using frozen eggs
The controlled rate freezing procedure, using the cryoprotectants propanediol and sucrose, is similar to the process used for embryo freezing and has been used successfully for over 15 years, resulting in the birth of thousands of babies. However, this success has not been translated into egg freezing, mainly due to the vulnerable state of the mature egg together with its size and water content.
An inability to respond to changes in the environment both within the egg and its surroundings during freezing or thawing results in rupture of the cell membrane, which is indicated by the survival rate. These conditions during freezing are also thought to cause rupture of components within the egg that are involved in the fertilisation process; the cortical granules ADDIN EN.CITE Schalkoff19895290Schalkoff, M. E.Oskowitz, S. P.Powers, R. D.Ultrastructural observations of human and mouse oocytes treated with cryopreservativesAnimalCryoprotective Agents/*adverse effectsCytoplasmic Granules/drug effects/ultrastructureDimethyl Sulfoxide/adverse effectsFemaleHumanIn VitroMiceOocytes/*drug effects/ultrastructureOrganelles/drug effects/ultrastructurePropylene Glycols/adverse effectsSupport, U.S. Gov't, P.H.S.Biol Reprod1989402379-93[81].
Similarly, fine filamentous structures that form the cytoskeleton just under the egg surface are also altered when exposed to the chemicals used in freezing; the cryoprotectant ADDIN EN.CITE Vincent1990b6070Vincent, C.Pruliere, G.Pajot-Augy, E.Campion, E.Garnier, V.Renard, J. P.1990bEffects of cryoprotectants on actin filaments during the cryopreservation of one-cell rabbit embryosCryobiology2719-23Actins/*drug effects/metabolism/ultrastructureAnimalCryopreservationCryoprotective Agents/*pharmacologyCytochalasin D/pharmacologyDimethyl Sulfoxide/pharmacologyEmbryo/cytology/*drug effects/metabolismIn VitroMicroscopy, ElectronPolymers/metabolismPropylene Glycols/pharmacologyRabbitsSolvents/pharmacologySupport, Non-U.S. Gov't[82]. Another component, the spindle, which holds the chromosomes in place ready for fertilisation, is sensitive to reduced temperature ADDIN EN.CITE Pickering19874940Pickering, S. J.Johnson, M. H.The influence of cooling on the organization of the meiotic spindle of the mouse oocyteAnimalBenzimidazoles/pharmacologyCentriolesChromatin/analysisColdFemaleHistocytochemistry*Meiosis/drug effectsMiceMicrotubules/drug effectsOocytes/*cytology/drug effects*Preservation, BiologicalSupport, Non-U.S. Gov'tTubulin/analysisHum Reprod198723207-16[83]. Damage to these components would compromise the eggs ability to be fertilised and could result in abnormal chromosome numbers after fertilisation.
However, much of this damage reported in these studies has been attributed to the use of an inferior cryoprotectant (DMSO), which has since been replaced by another cryoprotectant (propanediol), and also to differences in eggs between species. This will be discussed in more detail further on in this report.
Benefits of using frozen eggs
Embryo freezing has been well established for many years and is a highly successful technique for maximising the chance of pregnancy from a population of eggs while reducing the risk of multiple pregnancy. It is difficult to see that, in the near future, the results for egg freezing will surpass embryo freezing due to the ability to select embryos and the pressure to achieve a pregnancy quickly ADDIN EN.CITE Edgar200720800174258221442007AprHow should the clinical efficiency of oocyte cryopreservation be measured?430-5Reproductive Services/Melbourne IVF, Royal Women's Hospital, Carlton, Victoria 3053, Australia. david@mivf.com.auEdgar, D. H.Gook, D. A.Reprod Biomed OnlineAdultCryopreservation/*methodsEmbryo/metabolism*Embryo ImplantationFemaleFertilityFreezingHumansInfertility/*therapyMaleOocytes/*cytology/metabolismPregnancyPregnancy OutcomeTime FactorsTreatment Outcomehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17425822[84].
Clearly there is a benefit in freezing eggs in the situation where embryos cannot be formed due to absence of sperm for fertilisation ADDIN EN.CITE Gook199917950Gook, D. A.Edgar, D. H.1999Cryopreservation of the human female gamete: current and future issuesHum Reprod14122938-40.Cryopreservation/*methods/*trendsFemaleHuman*Oocytes[1] or in the case of young single women who have malignant conditions that threaten their fertility ADDIN EN.CITE Stern200619800164416874612006FebFertility preservation in female oncology patients15-23Reproductive Services and Melbourne IVF, The Royal Women's Hospital, Melbourne, Australia. kate.stern@mivf.com.auStern, C. J.Toledo, M. G.Gook, D. A.Seymour, J. F.Aust N Z J Obstet Gynaecolhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16441687[85]. There is also a benefit in freezing donated eggs for synchronisation with the recipient ADDIN EN.CITE Barritt200719820170949858712007JanReport of four donor-recipient oocyte cryopreservation cycles resulting in high pregnancy and implantation rates189 e13-7Department of Obstetrics and Gynecology, and Department of Reproductive Endocrinology and Infertility, Mount Sinai School of Medicine, New York, New York, USA.Barritt, J.Luna, M.Duke, M.Grunfeld, L.Mukherjee, T.Sandler, B.Copperman, A. B.Fertil SterilAdultCryopreservation/*methods/statistics & numerical dataFemaleFertilization in Vitro/*methods/*statistics & numerical dataHumansNew York/epidemiologyOocytes/cytology/*transplantationPregnancyPregnancy Outcome/*epidemiology*Pregnancy RateTissue Donors/statistics & numerical dataTransplantation/statistics & numerical dataTreatment Outcomehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17094985[52]. At present, these are the main situations in which egg freezing is used in all countries apart from Italy. However, the main benefit of egg freezing lies in the ethical problems associated with the creation and storage of multiple embryos. Egg freezing eliminates the dilemma patients face when discarding embryos, or legal issues relating to ownership of embryos following separation.
Lack of information
As stated previously, many of the earlier studies dealt with small numbers of patients, but this has recently altered with many of the Italian groups reporting egg freezing using a controlled rate method in larger numbers of patients (50100).
Similarly, although the interest in vitrification of human eggs is increasing, the reports in the literature are of small series of patients, which are generally a selected group of patients who have good quality eggs (egg donors). Larger numbers of non-selected patients are required to validate the procedure. There is also an absence of basic biological studies with human eggs assessing the cellular structures in which damage may occur following vitrification.
The literature lacks a comparison between fresh eggs and frozen eggs within the same clinic in which all other factors apart from the freezing of the egg are uniform. Attempts to provide this comparison have been presented in a couple of recent studies, but these studies are deficient in meaningful embryo quality assessment between fresh and frozen eggs. Data regarding any follow-up of postnatal and childhood development is completely absent.
Information from human studies
Efficacy
Survival, fertilisation, embryo development and implantation following egg freezing
The ultimate success of any assisted reproductive technology must be defined in terms of babies born. However, a number of other crucial criteria must be applied in order to fully understand the value and shortcomings of egg freezing. The controlled rate freezing procedure, using the cryoprotectants propanediol and sucrose ADDIN EN.CITE Gook19933040Gook, D. A.Osborn, S. M.Johnston, W. I.Cryopreservation of mouse and human oocytes using 1,2-propanediol and the configuration of the meiotic spindleAnimalCell Survival/drug effectsChromosome Abnormalities/chemically inducedCryopreservationCryoprotective Agents/*pharmacologyFemaleHumanMeiosis/*drug effectsMiceMitotic Spindle Apparatus/*drug effectsOocytes/cytology/*drug effectsPropylene Glycols/*pharmacologySupport, Non-U.S. Gov'tHum Reprod1993871101-9[86], heralded the reintroduction of egg freezing as a clinical procedure and culminated in the report of a normal live birth following thawing, fertilisation and transfer ADDIN EN.CITE Porcu19974990Porcu, E.Fabbri, R.Seracchioli, R.Ciotti, P. M.Magrini, O.Flamigni, C.1997Birth of a healthy female after intracytoplasmic sperm injection of cryopreserved human oocytesFertil Steril684724-6AdultCase Report*Cryopreservation*Cytoplasm*DeliveryEmbryo TransferFemaleFertilizationHumanMaleMicroinjections*MicromanipulationOocytes/*physiologyPregnancyReference Values*SpermatozoaSupport, Non-U.S. Gov't[19].
In these initial studies ADDIN EN.CITE Gook19943050Gook, D. A.Osborn, S. M.Bourne, H.Johnston, W. I.Fertilization of human oocytes following cryopreservation; normal karyotypes and absence of stray chromosomesCell Survival*Chromosome AberrationsComparative Study*CryopreservationFemale*Fertilization in VitroHuman*KaryotypingMaleOocytes/*physiology/ultrastructureSupport, Non-U.S. Gov'tTime FactorsHum Reprod199494684-91Gook19953070Gook, D. A.Schiewe, M. C.Osborn, S. M.Asch, R. H.Jansen, R. P.Johnston, W. I.Intracytoplasmic sperm injection and embryo development of human oocytes cryopreserved using 1,2-propanediolBlastocyst/physiologyCleavage Stage, Ovum*Cryopreservation*Cryoprotective AgentsCytoplasmEmbryo/*growth & developmentFemaleFertilization in Vitro/*methodsHumanMaleMicroinjectionsOocytes/*physiology/ultrastructure*Propylene GlycolsHum Reprod199510102637-41[87, 88], approximately 50 percent of frozen eggs survived when thawed, 50 percent of these were able to be fertilised by a sperm in the laboratory and go on to produce an embryo. However, only 25 percent of these embryos continued cleaving to the implantation stage (blastocyst). This freezing procedure has been the most widely used clinical approach to date, resulting in 43 births from over 460 women treated ADDIN EN.CITE Tucker19965880http://www.ncbi.nlm.nih.gov/cgi-bin/Entrez/referer?http://www.oup.co.uk/jnls/list/humrep/hdb/Volume_11/Issue_07/111513.sgm.abs.htmlTucker, M.Wright, G.Morton, P.Shanguo, L.Massey, J.Kort, H.Preliminary experience with human oocyte cryopreservation using 1,2- propanediol and sucroseCell AgingCell SurvivalCryopreservation/*methods*Cryoprotective AgentsCytoplasmEmbryo TransferEvaluation StudiesFemaleFertilization in VitroFetal DevelopmentHumanIn VitroMaleMicroinjections*OocytesPregnancy*Propylene GlycolsSpermatozoa*SucroseHum Reprod19961171513-5Porcu19974990Porcu, E.Fabbri, R.Seracchioli, R.Ciotti, P. M.Magrini, O.Flamigni, C.1997Birth of a healthy female after intracytoplasmic sperm injection of cryopreserved human oocytesFertil Steril684724-6AdultCase Report*Cryopreservation*Cytoplasm*DeliveryEmbryo TransferFemaleFertilizationHumanMaleMicroinjections*MicromanipulationOocytes/*physiologyPregnancyReference Values*SpermatozoaSupport, Non-U.S. Gov'tAntinori1998510Antinori, SDani, GSelman, H AVidali, AAntinori, MCerusico, CVersaci, C1998Pregnancies after sperm injection into cryopreserved human oocytes.Human Reproduction13157-158. Abst P-55, 14th Annual ESHRE Meetingcryopreservation,oocyte,human,pregnancyVidali199820660Vidali, A.Dani, G.Antinori, M.Cerusico, F.Versaci, C.Antinori, S.1998Oocyte cryopreservation is a viable alternative option for patients who refuse embryo freezingFertility and Sterility70suppl 1S138Nawroth19981937095989597741998AprPregnancy after intracytoplasmatic sperm injection (ICSI) of cryopreserved human oocytes462-3Clinic for Obstetrics and Gynecology, Stralsund Municipal Hospital plc., Germany.Nawroth, F.Kissing, K.Acta Obstet Gynecol ScandAdult*CryopreservationCytoplasmFemaleHumansInjections/methodsInsemination, Artificial, Homologous/*methodsMale*OligospermiaOocytes/*pathologyPregnancy*Sperm-Ovum Interactionshttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=9598959Polak de Fried19984980Polak de Fried,ENotrica,JRubinstein,MMarazzi,A1998Oocyte cryopreservation program: Removal vs non removal of cumulus corona complexFertility and Sterility70, Suppl. 1Suppl. 1S148. Abst P-71 ASRM MeetingPorcu1998490Porcu, EFabbri, RSeracchioli, RCiotti, P MPetracchi, SSavelli, LGhi, TFlamigni, C1998Birth of six healthy children after intracytoplasmic sperm injection of cryopreserved human oocytes.Human Reproduction13124. Abst O-240, 14th Annual ESHRE Meeting.cryopreservation,oocyte,pregnancy,humanTucker19985890Tucker, M. J.Wright, G.Morton, P. C.Massey, J. B.1998Birth after cryopreservation of immature oocytes with subsequent in vitro maturationFertil Steril703578-9AdultCase ReportCell Aging/physiology*CryopreservationFeasibility StudiesFemale*Fertilization in VitroHumanLabor/*physiologyPregnancyYoung19986300Young, E.Kenny, A.Puigdomenech, E.Van Thillo, G.Tiveron, M.Piazza, A.Triplet pregnancy after intracytoplasmic sperm injection of cryopreserved oocytes: case reportAdultCase Report*CryopreservationCytoplasmFemaleHumanInfertility, Female/*therapyMaleMicroinjections*OocytesPregnancy*Pregnancy, Multiple*Sperm-Ovum Interactions*TripletsFertil Steril1998702360-1Wurfel1999193801052237812191999[Fertilization of cryopreserved and thawed human oocytes (Cryo-Oo) by injection of spermatozoa (ICSI)--medical management of sterility and case report of a twin pregnancy]444-8Frauenklinik Dr. Wilhelm Krusmann, Munchen.Wurfel, W.Schleyer, M.Krusmann, G.Hertwig, I. V.Fiedler, K.Fertilisation von kryokonservierten und aufgetauten humanen Oozyten (Kryo-Oo) vermittels Injektion von Spermatozoen (ICSI)--Sterilitatstherapeutisches Management und Kasuistik einer Zwillingsschwangerschaft.Zentralbl GynakolAdultCesarean SectionCryopreservationEnglish AbstractFemaleFertilization in VitroHumansInfant, Newborn*Infertility, FemaleMale*OocytesPregnancySperm Injections, Intracytoplasmic/*methodsSpermatozoa/physiology*Twins, Dizygotichttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10522378Porcu20008630Porcu,EFabbri,RMarsella,TBalicchia,BDe Cesare,DGiunchi,SDamiano,GCaracciolo,DFlamigni, C2000Clinical experience and applications of oocyte cryopreservation.Mol Cell Endocrinol16933-37Chia200018020Chia,CMChan,WBQuah,ECheng,LC2000Triploid pregnancy after ICSI of frozen testicular spermatozoa into cryopreserved human oocytes. Case Report.Hum Reprod1591962-1964Porcu200118010Porcu, EFabbri, RCiotti,PGiunchi,SFratto,RCaracciolo,D2001Four healthy children from frozen human oocytes and frozen human sperms.Fertility and Sterility76, Suppl. 1Suppl. 1S76. Abst O-203, ASRM Meeting.Porcu200218140Porcu, EFabbri, RCiotti,PMFrau, FDe Cesare, RVenturoli, S2002Oocytes or embryo storage.Fertility and Sterility783 Suppl 1S15, Abst O-38Huttelova200319360129480892082003AugMore successful oocyte freezing293Pronatal, Prague 4, Czech Republic.Huttelova, R.Becvarova, V.Brachtlova, T.J Assist Reprod Genet*CryopreservationFemaleHumans*OocytesOvarian Folliclehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=12948089Notrica200318890Notrica,JKanzepolsky,LDivita,ANeuspiller,FPolak de Fried,E2003A healthy female born after ICSI of a cryopreserved oocyte and cryopreserved spermatozoa banked prior to radiotherapy in a patient with a seminoma: A case report.Fertility and Sterility80 supl 3S149 P-86Allan200419340155983074462004DecRe: Case report: Pregnancy from intracytoplasmic injection of a frozen-thawed oocyte588Allan, J.Aust N Z J Obstet GynaecolAdult*CryopreservationFemaleFertilization in Vitro/methodsFollow-Up StudiesHumansInfertility, Female/therapy*OocytesPregnancy/*physiology*ReligionSperm Injections, Intracytoplasmic/*methodshttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15598307Borini200419250153747028232004SepPregnancies and births after oocyte cryopreservation601-5Tecnobios Procreazione, Via Dante 15, 40125 Bologna, Italy. borini@tecnobios.itBorini, A.Bonu, M. A.Coticchio, G.Bianchi, V.Cattoli, M.Flamigni, C.Fertil SterilCell Survival*Cryopreservation/methodsEmbryo ImplantationFemaleHumansOocytes/*cytology*PregnancyRetrospective Studies*Sperm Injections, Intracytoplasmichttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15374702Kan200419350151914554432004JunPregnancy from intracytoplasmic injection of a frozen-thawed oocyte262-3IVF Australia, Southern Sydney, Sydney, Australia.Kan, A.Kilani, S.Tilia, L.Mitchell, F.Burns, K.Chapman, M.Aust N Z J Obstet GynaecolAdult*Cryopreservation*Embryo TransferFemaleFertilization in Vitro/*methodsHumansOocytes/*physiology*PregnancyPregnancy OutcomeSperm Injections, Intracytoplasmic/*methodshttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15191455Miller200419230152370148212004JulPregnancy after cryopreservation of donor oocytes and preimplantation genetic diagnosis of embryos in a patient with ovarian failure211-4Reproductive Medicine Associates of New Jersey, Morristown, New Jersey 07962, USA. kmiller@rmanj.comMiller, K. A.Elkind-Hirsch, K.Levy, B.Graubert, M. D.Ross, S. J.Scott, R. T., Jr.Fertil SterilAdultAneuploidy*CryopreservationEmbryo/physiologyEmbryo TransferFemaleFertilization in VitroHumans*Oocyte Donation*OocytesOvarian Failure, Premature/*therapy*Pregnancy*Preimplantation DiagnosisSperm Injections, IntracytoplasmicUltrasonography, Prenatalhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15237014De Santis200720040172073321412007JanOocyte cryopreservation: clinical outcome of slow-cooling protocols differing in sucrose concentration57-63Vita-Salute University, IVF Unit, H S Raffaele, Via Olgettina 60, 20132 Milan, Italy. desantis.lucia@hsr.itDe Santis, L.Cino, I.Rabellotti, E.Papaleo, E.Calzi, F.Fusi, F. M.Brigante, C.Ferrari, A.Reprod Biomed Onlinehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17207332Greco200720850179808712007Nov 1Birth of a healthy boy after fertilization of cryopreserved oocytes with cryopreserved testicular spermatozoa from a man with nonmosaic Klinefelter syndromeCenter for Reproductive Medicine, European Hospital, Rome, Italy.Greco, E.Iacobelli, M.Rienzi, L.Menchini Fabris, G. F.Tesorio, N.Tesarik, J.Fertil Sterilhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17980871[19, 2137, 57, 8991]. Just over 4000 eggs have been frozen and thawed, with 50 percent surviving the procedure.
Following a procedure in which the sperm is directly injected inside the egg (Intra cytoplasmic sperm injection (ICSI)), the normal process of fertilisation occurred in 54 percent of the surviving eggs.
ICSI is the preferred method of fertilising frozen eggs. The vast majority (85percent) of these fertilised eggs subsequently formed early stage (28 cells) embryos that were transferred to the patient. The proportion of embryos transferred that subsequently go on to form a detectable foetus is referred to as the implantation rate. This is an early stage of pregnancy defined by the detection of a foetal heartbeat, using ultrasound scanning. The implantation rate of embryos formed from frozen eggs was approximately 10 percent. So, based on the numbers of surviving eggs, the number of those that fertilised and developed and the number of embryos that formed a foetus when transferred to the patient, it can be estimated that approximately two foetuses would result from the thawing of 100 frozen eggs. Based on published data from approximately the same time period ADDIN EN.CITE Edgar200018490Edgar, D HBourne, HSpeirs, A LMcBain, J C2000A quantitative analysis of the impact of cryopreservation on the implantation potential of human early cleavage stage embryos.Human Reproduction15175-179[92], this can be compared to approximately six foetuses from 100 non-frozen eggs if they were exposed to sperm and the embryos were transferred or approximately four foetuses from 100 non-frozen eggs if they were exposed to sperm, frozen and thawed as embryos and transferred.
Using this model, it could be considered that egg freezing is approximately half as effective as embryo freezing and a third as effective as the use of fresh eggs.
New methods
Recently a number of modifications to this original method have been reported. These have aimed at improving the efficiency of removing water (dehydration) before freezing by using higher levels of the cryoprotectant sucrose. Although the number of eggs frozen using some of these modifications is lower, there is a general trend towards improved results. Doubling the sucrose level has achieved an improved survival rate of 71 percent and a higher fertilisation rate of 80percent ADDIN EN.CITE Yang199818110Yang, DSBlohm, PLWinslow, KLCramer, L1998A twin pregnancy after microinjection of human cryopreserved oocyte with a specially developed oocyte cryopreservation regime.Fertility and Sterility703, Suppl 1S239, Abst P-357Porcu19995000Porcu, E.Fabbri, R.Ciotti, P. M.Petracchi, S.Seracchioli, R.Flamigni, C.Ongoing pregnancy after intracytoplasmic sperm injection of epididymal spermatozoa into cryopreserved human oocytesAdultCase Report*CryopreservationEpididymis/physiologyFemale*Fertilization in VitroHumanMaleMicroinjectionsOocytes/*physiologyPregnancySpecimen HandlingSpermatozoa/physiologyJ Assist Reprod Genet1999165283-5Kyono200120390Kyono, K.Fukunaga, N.Haigo, K.Chiba, S.Sato, T.2001Pregnancy and delivery of a healthy female infant after intracytoplasmic sperm injection into cryopreserved human oocytes.Jpn J Fertil Steril46171-177Winslow200118000Winslow, KLYang, DBlohm, PLBrown, SEJossim, PNguyen, K2001Oocyte cryopreservation /a three year follow up of sixteen births.Fertility and Sterility76, Suppl. 13, Supp1S120. Abst P-28, ASRM Meeting.Yang200218130Yang, DSWinslow, KLBlohm, PLBrown, SENguyen, KBrubaker, C2002Oocyte donation using cryopreserved donor oocytes.Fertility and Sterility783, Suppl 1S14, Abst O-37Bianchi200719990172073331412007JanDifferential sucrose concentration during dehydration (0.2 mol/l) and rehydration (0.3 mol/l) increases the implantation rate of frozen human oocytes64-71Tecnobios Procreazione, Via Dante 15, 40125 Bologna, Italy.Bianchi, V.Coticchio, G.Distratis, V.Di Giusto, N.Flamigni, C.Borini, A.Reprod Biomed Onlinehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17207333Gook200720000171928352412007JanLive birth following transfer of a cryopreserved embryo generated from a cryopreserved oocyte and a cryopreserved sperm: Case report43-45Reproductive Services, Royal Women's Hospital, 132 Grattan Street, Carlton, Victoria, 3053, Australia.Gook, D. A.Hale, L.Edgar, D. H.J Assist Reprod Genethttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17192835Montag200620010Montag, M.van der Ven, K.Dorn, C.Isachenko, V.Isachenko, E.van der Ven, H.2006Birth after double cryopreservation of human oocytes at metaphase II and pronuclear stagesFertil Steril853751 e5-7Mar16500354Adult*CryopreservationEmbryo TransferFemaleHumansInfant, NewbornMale*MetaphaseOocytes/*cytology*ParturitionPregnancy*ProphaseSperm Injections, Intracytoplasmichttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16500354Department of Gynecological Endocrinology and Reproductive Medicine, University of Bonn, Bonn, Germany. Markus.Montag@ukb.uni-bonn.deCoticchio200720860Coticchio, G.Distratis, V.Bianchi, V.Bonu, A.Borini, A.2007Fertilization and early developmental ability of cryopreserved human oocytes is not affected compared to sibling fresh oocytes.Fertility and Sterility88Suppl 1.P-700[38, 4044, 60, 93, 94].
A slightly higher proportion of the fertilised eggs form embryos relative to the low sucrose method, and the above improvements result in double the number of embryos (53) produced per 100 eggs compared to the low sucrose procedure (23) and more of these embryos implant (implantation rate of 17 percent). This attrition rate would result in nine foetuses from 100 frozen eggs, which is equivalent to the outcome from non-frozen eggs observed with recent improvements in culture methods (unpublished observation). Again, more recent in-house data would be required to make a meaningful comparison. The major group using this procedure has had 50 babies born from this procedure (personal communication).
Further increasing the sucrose level to three times that reported in the initial procedure has been trialled more extensively ADDIN EN.CITE Fosas200318390Fosas, NMarina,FTorres,P.JJove,IMartin,PPerez,NArnedo,NMarina,S2003The births of five Spanish babies from cryopreserved donated oocytes.Hum Reprod1871417-1421Chen200519020157906042072005JulObservational clinical follow-up of oocyte cryopreservation using a slow-freezing method with 1,2-propanediol plus sucrose followed by ICSI1975-80Department of Obstetrics and Gynecology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan.Chen, S. U.Lien, Y. R.Chen, H. F.Chang, L. J.Tsai, Y. Y.Yang, Y. S.Hum Reprodhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15790604Li2005192601609632120122005DecCryopreserved oocytes of infertile couples undergoing assisted reproductive technology could be an important source of oocyte donation: a clinical report of successful pregnancies3390-4Reproduction and Genetic Center, First Hospital of Peking University, Peking University, Beijing, China. l_xiaoh@yahoo.com.cnLi, X. H.Chen, S. U.Zhang, X.Tang, M.Kui, Y. R.Wu, X.Wang, S.Guo, Y. L.Hum Reprodhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16096321Tjer200519220158666018352005MayBirth of a healthy baby after transfer of blastocysts derived from cryopreserved human oocytes fertilized with frozen spermatozoa1547-9Department of Obstetrics and Gynecology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin NT, Hong Kong SAR, China.Tjer, G. C.Chiu, T. T.Cheung, L. P.Lok, I. H.Haines, C. J.Fertil SterilAdultCryopreservation/*methods*Embryo TransferFemaleHumansInfant, Newborn*Live BirthMale*OocytesPregnancy*Spermatozoahttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15866601Levi Setti200619280162393152122006FebCryopreservation of supernumerary oocytes in IVF/ICSI cycles370-5UO di Medicina della Riproduzione, IRCCS Istituto Clinico Humanitas, Rozzano (Milano), Italy. paolo.levi_seti@humanitas.itLevi Setti, P. E.Albani, E.Novara, P. V.Cesana, A.Morreale, G.Hum Reprodhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16239315Borini2006b19190Borini, A.Sciajno,R.Bianchi, V.Sereni,EFlamigni, C.Coticchio, G.2006bCinical outcome of oocyte cryopreservation after slow cooling with a protocol utilizing a high sucrose concentrationHuman Reproduction212512-517Chamayou200620020167928491262006JunComparison of in-vitro outcomes from cryopreserved oocytes and sibling fresh oocytes730-6Unita di Medicina della Riproduzione - Fondazione HERA, Viale Marco Polo 39/A, 95126 Catania, Italy. angugl@tin.itChamayou, S.Alecci, C.Ragolia, C.Storaci, G.Maglia, E.Russo, E.Guglielmino, A.Reprod Biomed OnlineAdult*CryopreservationEmbryonic DevelopmentFemaleFertilization in VitroHumansMaleOocytes/*physiologyPregnancyhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16792849La Sala200620030170701948652006NovOutcome of 518 salvage oocyte-cryopreservation cycles performed as a routine procedure in an in vitro fertilization program1423-7Department of Obstetrics and Gynecology, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy.La Sala, G. B.Nicoli, A.Villani, M. T.Pescarini, M.Gallinelli, A.Blickstein, I.Fertil SterilAdultCell SurvivalCohort StudiesCryopreservation/*methodsFemaleFertilization in Vitro/*methods/*statistics & numerical dataHumansInfertility/epidemiology/*therapyItaly/epidemiologyLive Birth/*epidemiologyMiddle AgedOocytes/*cytology/*transplantationPregnancyTreatment Outcomehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17070194De Santis200720040172073321412007JanOocyte cryopreservation: clinical outcome of slow-cooling protocols differing in sucrose concentration57-63Vita-Salute University, IVF Unit, H S Raffaele, Via Olgettina 60, 20132 Milan, Italy. desantis.lucia@hsr.itDe Santis, L.Cino, I.Rabellotti, E.Papaleo, E.Calzi, F.Fusi, F. M.Brigante, C.Ferrari, A.Reprod Biomed Onlinehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17207332Barritt200719820170949858712007JanReport of four donor-recipient oocyte cryopreservation cycles resulting in high pregnancy and implantation rates189 e13-7Department of Obstetrics and Gynecology, and Department of Reproductive Endocrinology and Infertility, Mount Sinai School of Medicine, New York, New York, USA.Barritt, J.Luna, M.Duke, M.Grunfeld, L.Mukherjee, T.Sandler, B.Copperman, A. B.Fertil SterilAdultCryopreservation/*methods/statistics & numerical dataFemaleFertilization in Vitro/*methods/*statistics & numerical dataHumansNew York/epidemiologyOocytes/cytology/*transplantationPregnancyPregnancy Outcome/*epidemiology*Pregnancy RateTissue Donors/statistics & numerical dataTransplantation/statistics & numerical dataTreatment Outcomehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17094985Konc200719790172073241412007JanDoes oocyte cryopreservation have a future in Hungary?11-3Infertility and IVF Centre of Buda, Saint Janos Hospital, Budapest 1125, Hungary.Konc, J.Kanyo, K.Cseh, S.Reprod Biomed Onlinehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17207324Lappi200720870Lappi, M.Magli, M.C.Gianaroli, L.Resta, S.Capoti, A.Borghi, E.Ferraretti, A.P.2007Factors affecting the outcome of oocyte freezingHuman Reproduction22suppl 1.i156, P-398Fosas200720880Fosas, N.Marina, F.Sunol, J.Garcia, J.Marina, D.Marina, S.2007Comparison between fresh and cryopreserved donated oocytes.Human Reproduction22suppl 1.i75, O-185Novara200720890Novara, P.V.Albani, ECesana, ASmeraldi, A.Negri, P. E.Levi Setti, P. E.2007Oocyte cryopreservation and testicular cyropreserved spermatozoa.Fertility and Sterility88suppl 1.S346, P-718Ding200620900Ding, J.Dmowski, W.Rana, N.2006Preganacy and delivery after oocyte cryopreservation with slow freezing method.Fertility and Sterility86suppl 2.S206, P-201Briton-Jones200620910Briton-Jones, C.M.Yeung, Q.S.Steinberg, J.m.2006Frozen donor ooctes to rescue cycles for patients with a known poor- prognosis for oocyte retrieval.Fertility and Sterility86suppl 2.S207, P-204[15, 36, 4753, 59, 61, 6367]. Again, higher survival (73 percent) and fertilisation (73 percent) rates are achieved. Although a high number of embryos are generated (48 per 100 eggs), fewer of the embryos implant, reducing the final outcome to three foetuses per 100thawed eggs. To date, 54 babies have been born using this modification.
Another approach has been to alter the salt solution the eggs are exposed to in combination with sucrose at each of the above concentrations; 0.1M ADDIN EN.CITE Quintans200218420Quintans, C JDonaldson, M JBertolino, M VPasqualini, R S2002Birth of two babies using oocytes that were cryopreserved in a choline-based freezing medium.Human Reproduction17123149-3152[54], 0.2M ADDIN EN.CITE Boldt200620050168201181312006JulHuman oocyte cryopreservation: 5-year experience with a sodium-depleted slow freezing method96-100Assisted Fertility Services, Community Health Network, Indianapolis, IN, USA. jboldt@ecommunity.comBoldt, J.Tidswell, N.Sayers, A.Kilani, R.Cline, D.Reprod Biomed OnlineCryopreservation/*methodsCulture MediaEmbryo TransferFemaleHumans*OocytesPregnancy*Reproductive Techniques, AssistedSodiumTime Factorshttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16820118Petracco200619830170076681342006OctComparison of embryo quality between sibling embryos originating from frozen or fresh oocytes497-503Fertilitat-Reproductive Medicine Centre, Porto Alegre, RS. Brazil.Petracco, A.Azambuja, R.Okada, L.Michelon, J.Oliani, A.Badalotti, M.Reprod Biomed OnlineAdultCleavage Stage, OvumCryopreservation/*methodsEmbryo/*physiologyFemaleHumansOocytes/*physiologyPregnancyPregnancy OutcomeRetrospective Studies*Siblings*Sperm Injections, Intracytoplasmichttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17007668[55, 62] and 0.3M ADDIN EN.CITE Boldt200620050168201181312006JulHuman oocyte cryopreservation: 5-year experience with a sodium-depleted slow freezing method96-100Assisted Fertility Services, Community Health Network, Indianapolis, IN, USA. jboldt@ecommunity.comBoldt, J.Tidswell, N.Sayers, A.Kilani, R.Cline, D.Reprod Biomed OnlineCryopreservation/*methodsCulture MediaEmbryo TransferFemaleHumans*OocytesPregnancy*Reproductive Techniques, AssistedSodiumTime Factorshttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16820118Allen200720920Allen, R.B.Francis, M.M.Chung, K.Fogle, R.H.Kalan, M.J.Paulson, R.J.2007Oocyte cryopreservation: comparison of outcomes using autologous vs. donor oocytes.Fertility and Sterility88suppl 1.S352, P-738Jain200720930Jain, J.K.Francis, M.M.McConnell, M.Quinn, p.2007Initial experience of a commerical donor egg bank.Fertility and Sterility88suppl 1.S346, P-719[55, 68, 69]. Altering the salt solution produced no further improvement in the survival, fertilisation and embryo development rates above that for the corresponding sucrose level alone. However, the implantation rates differ when compared to the corresponding sucrose alone. The 0.1M and 0.3M sucrose levels together with the salt modification resulted in a two-fold improvement in the implantation rate compared to sucrose alone. In contrast, a lower implantation rate was achieved when the double sucrose combined with the salt modification was used (11 percent) relative to the double sucrose alone. Finally, the culmination of these rates for both the 0.1M and 0.3M sucrose in the modified salt media, results in six foetuses/100 eggs thawed.
Caution should be exercised in interpreting these results since all modified salt studies are on relatively small numbers of eggs (~200) and only 16 births have been reported.
Vitrification
Although previously the same could have been said of vitrification, at the recent American Society for Reproductive Medicine meeting (October 2007), 173births were reported from a vitrification procedure using similar cryoprotectants to the controlled rate freezing procedure (propanediol [PROH] and sucrose) together with another cryoprotectant; ethylene glycol (EG) ADDIN EN.CITE Huang200721000Huang, J. Y.Ruvalcaba Castellon, L.A.Garcia Amador, M. I.Lucena, E.Saa, A.Chian, R. C.2007Obstetric and perinatal outcomes in pregnancies conceived by vitrified oocytes in three centers.Fertility and Sterility88suppl 1.S352, P-737[95].
A further 39 births have been reported following vitrification in a solution where the propanediol has been replaced with dimethyl sulphoxide (DMSO) ADDIN EN.CITE Kuleshova199918080Birth following vitrification of a small number of human oocytes: case reportKuleshova, L.Gianaroli, L.Magli, C.Ferraretti, A.Trounson, A.AdultCase ReportCryopreservation/*methodsEmbryo TransferFemale*Fertilization in VitroHumanInfertility, Female/genetics/therapy*LaborMiddle AgeOocyte Donation*OocytesPregnancySperm Injections, IntracytoplasmicSupport, Non-U.S. Gov'tTreatment FailureHum Reprod199914123077-9.Yoon200318580127988787962003JunLive births after vitrification of oocytes in a stimulated in vitro fertilization-embryo transfer program1323-6College of Medicine, Pochon CHA University and Infertility Medical Center of CHA General Hospital, Seoul, South Korea. tkyoon@cha.ac.krYoon, T. K.Kim, T. J.Park, S. E.Hong, S. W.Ko, J. J.Chung, H. M.Cha, K. Y.Fertil SterilAdultCryopreservation/*methods*Embryo TransferFemale*Fertilization in VitroHumanInfant, Newborn*OocytesPregnancySperm Injections, IntracytoplasmicSupport, Non-U.S. Gov'thttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=12798878Kuwayama200519300161766681132005SepHighly efficient vitrification method for cryopreservation of human oocytes300-8Kato Ladies' Clinic, Tokyo, Japan. masaabc@bokkoame.ne.jpKuwayama, M.Vajta, G.Kato, O.Leibo, S. P.Reprod Biomed OnlineAnimalsBlastocyst/cytology/physiologyCattleComparative StudyCryopreservation/instrumentation/*methodsEmbryo TransferEthylene Glycol/pharmacologyFemaleHumansIn Situ Hybridization, FluorescenceMaleOocytes/drug effects/*physiologyPregnancyPregnancy OutcomePregnancy RateSperm Injections, Intracytoplasmichttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16176668Kyono200519210162138608442005OctSuccessful pregnancy and delivery after transfer of a single blastocyst derived from a vitrified mature human oocyte1017Department of Gynecology and Urology, Ladies Clinic Kyono, Miyagi, Japan. info@ivf-kyono.or.jpKyono, K.Fuchinoue, K.Yagi, A.Nakajo, Y.Yamashita, A.Kumagai, S.Fertil SterilAdult*Blastocyst/cytologyCryopreservation/*methodsDelivery, Obstetric/methods*Embryo TransferFemaleHumansInfant, Newborn*Live BirthMale*Oocytes/cytologyPregnancyhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16213860Selman200619850169630448642006OctOngoing pregnancies after vitrification of human oocytes using a combined solution of ethylene glycol and dimethyl sulfoxide997-1000Centro Sterilita e Fecondazione Assistita Policlinico di Perugia, University of Perugia, Perugia, Italy. selmanha@yahoo.comSelman, H.Angelini, A.Barnocchi, N.Brusco, G. F.Pacchiarotti, A.Aragona, C.Fertil SterilAdultCell Survival/drug effectsCells, CulturedCryopreservation/*methodsCryoprotective Agents/administration & dosageDimethyl Sulfoxide/*administration & dosageDrug CombinationsEthylene Glycol/*administration & dosageFemaleFertilization in Vitro/*methodsHumansInfertility/*therapyOocytes/cytology/*drug effects/*transplantationPregnancyPregnancy OutcomeTreatment Outcomehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16963044Antinori200719840172073351412007JanCryotop vitrification of human oocytes results in high survival rate and healthy deliveries72-9International Associated Research Institute for Human Reproduction Infertility Unit Day Hospital, Via Timavo No.2, Rome, Italy. monica_antinori@hotmail.itAntinori, M.Licata, E.Dani, G.Cerusico, F.Versaci, C.Antinori, S.Reprod Biomed Onlinehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17207335Cobo200720940178898652007Sep 21Comparison of concomitant outcome achieved with fresh and cryopreserved donor oocytes vitrified by the Cryotop methodIVI Universidad de Valencia, Valencia, Spain.Cobo, A.Kuwayama, M.Perez, S.Ruiz, A.Pellicer, A.Remohi, J.Fertil Sterilhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17889865Yoon200720950173500078842007OctSurvival rate of human oocytes and pregnancy outcome after vitrification using slush nitrogen in assisted reproductive technologies952-6Fertility Center of CHA General Hospital, CHA Research Institute, Pochon CHA University, College of Medicine, Seoul, Korea. tkyoon@cha.ac.krYoon, T. K.Lee, D. R.Cha, S. K.Chung, H. M.Lee, W. S.Cha, K. Y.Fertil SterilAdultCryopreservation/*methodsEmbryo TransferFemaleHumansNitrogen*OocytesPregnancy*Pregnancy Outcome*Reproductive Techniques, Assistedhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17350007Sher200720960Sher, G.Keskintepe, L.Mukaida, T.Keskintepe, M.Ginsburg, M.Maassarani, G.2007Selective vitrification of euploid oocytes markedly improves their post -warming viability and post-fertilization pregnancy generating potential ,thereby opening the door to commercial egg banking.Fertility and Sterility88suppl 1.S343, P-711.[70, 71, 73, 7577, 79, 80, 96]. Previously, all studies reported were on small numbers of eggs (< 100) ADDIN EN.CITE Kuleshova199918080Birth following vitrification of a small number of human oocytes: case reportKuleshova, L.Gianaroli, L.Magli, C.Ferraretti, A.Trounson, A.AdultCase ReportCryopreservation/*methodsEmbryo TransferFemale*Fertilization in VitroHumanInfertility, Female/genetics/therapy*LaborMiddle AgeOocyte Donation*OocytesPregnancySperm Injections, IntracytoplasmicSupport, Non-U.S. Gov'tTreatment FailureHum Reprod199914123077-9.Kuwayama200519300161766681132005SepHighly efficient vitrification method for cryopreservation of human oocytes300-8Kato Ladies' Clinic, Tokyo, Japan. masaabc@bokkoame.ne.jpKuwayama, M.Vajta, G.Kato, O.Leibo, S. P.Reprod Biomed OnlineAnimalsBlastocyst/cytology/physiologyCattleComparative StudyCryopreservation/instrumentation/*methodsEmbryo TransferEthylene Glycol/pharmacologyFemaleHumansIn Situ Hybridization, FluorescenceMaleOocytes/drug effects/*physiologyPregnancyPregnancy OutcomePregnancy RateSperm Injections, Intracytoplasmichttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16176668Kyono200519210162138608442005OctSuccessful pregnancy and delivery after transfer of a single blastocyst derived from a vitrified mature human oocyte1017Department of Gynecology and Urology, Ladies Clinic Kyono, Miyagi, Japan. info@ivf-kyono.or.jpKyono, K.Fuchinoue, K.Yagi, A.Nakajo, Y.Yamashita, A.Kumagai, S.Fertil SterilAdult*Blastocyst/cytologyCryopreservation/*methodsDelivery, Obstetric/methods*Embryo TransferFemaleHumansInfant, Newborn*Live BirthMale*Oocytes/cytologyPregnancyhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16213860Selman200619850169630448642006OctOngoing pregnancies after vitrification of human oocytes using a combined solution of ethylene glycol and dimethyl sulfoxide997-1000Centro Sterilita e Fecondazione Assistita Policlinico di Perugia, University of Perugia, Perugia, Italy. selmanha@yahoo.comSelman, H.Angelini, A.Barnocchi, N.Brusco, G. F.Pacchiarotti, A.Aragona, C.Fertil SterilAdultCell Survival/drug effectsCells, CulturedCryopreservation/*methodsCryoprotective Agents/administration & dosageDimethyl Sulfoxide/*administration & dosageDrug CombinationsEthylene Glycol/*administration & dosageFemaleFertilization in Vitro/*methodsHumansInfertility/*therapyOocytes/cytology/*drug effects/*transplantationPregnancyPregnancy OutcomeTreatment Outcomehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16963044[71, 73, 75, 77]. This together with minor differences in methodology, which may have a significant impact on the outcome, made meaningful comparisons difficult. However, there appear to now be three main streams of methodology and a significant number of eggs (> 200) vitrified with each (1. EG, 2. EG + DMSO, 3.EG+ PROH).
Survival and fertilisation rates are slightly lower in both the EG and EG + PROH (~75percent for each) compared with the EG + DMSO procedure (93 percent and 87 percent respectively). With one of these procedures (EG + PROH), only half the fertilised eggs formed embryos, therefore generating only 30 embryos/ 100eggs and four implantations/ 100eggs, which is similar to some of the controlled rate freezing procedure results.
Although better development rates were observed with the other procedures, only slightly more implantations, that is, five/ 100 eggs would be generated with the EG method due to a lower implantation rate of 10 percent. At present, the EG+DSMO procedure is achieving the highest rates, generating 75 embryos and 12 implantations/100 eggs. In contrast to the controlled rate and other vitrification studies, eggs vitrified in the EG+DMSO procedure were all obtained from young donors and are highly likely to be of higher quality than those from older infertile women, which may bias the data. Although suggestive of a marked improvement, only 22 babies have been reported from the EG+DMSO procedure.
Much larger studies using these vitrification methods are needed to establish whether these improvements can be maintained for all patients and whether the pregnancies reported continue to term deliveries.
Live birth
As stated previously, many of the studies generally report pregnancies, and if births have occurred prior to publication these are also included. Therefore, the numbers of births are always significantly lower than the numbers of pregnancies. It is important to establish that the new methods result in pregnancies that progress to full term. However, the small numbers of babies born from each modification make it difficult to generate meaningful birth rates for each modification. At present, the only number that provides a reasonable indication of live birth rate is the overall total, which is 1.3 births per 100 eggs. This is approximately half the rate estimated for the use of fresh eggs.
Health risks
Potential side effects from using frozen eggs.
The potential side effects that occur in the process of collecting eggs for freezing are similar to IVF. The stimulation protocol to induce multiple follicular development is identical to that utilised in the IVF programme. Consequently, the side effect or risk profile is the same as for the IVF programme up to and including the egg collection procedure. Risks associated with the process of ovarian hyperstimulation and egg collection can include an adverse reaction to the medication or over response to the medication. An excessive response to the ovulatory stimulants may subsequently lead to the ovarian hyperstimulation syndrome.
The ovarian hyperstimulation syndrome is characterised by abdominal distension, fluid retention and associated alteration of kidney, liver and blood clotting functions. In approximately 5 percent of patients, we would expect to obtain 20 or more eggs from the procedure. It is estimated that about 5 percent of those patients will require hospitalisation for pain control, fluid replacement and maintenance until the hyperstimulation phase passes [138].
The risk of ovarian hyperstimulation in these patients will be less than for the general IVF population. The reason for this is that if a transfer procedure utilising fresh embryos is undertaken and a pregnancy occurs, then this exacerbates the syndrome. In effect, the freezing of eggs will reduce the incidence of severe and later stage ovarian hyperstimulation.
Potential risks and side effects at the time of the egg collection procedure include pelvic infection, which may lead to ovarian abscess, peritonitis and/or pelvic abscess. The occurrence of these side effects is rare, with a reported incidence of less than one in five thousand cases [115]. Vaginal and/or pelvic bleeding and the need for a blood transfusion and/or abdominal or other surgery are rare.
The reported incidence of the serious side effects of damage to ovaries, bowel, bladder or other internal organs adjacent to the ovaries and subsequent need for abdominal or other surgery is rare at less than one per ten thousand cases [115].
Potential side effects following an egg collection procedure would include deep venous thrombosis or pulmonary embolism.
As discussed above, the occurrence of risk from these procedures is anticipated to be the same as the occurrence of risk for the IVF procedure given the common pathway with regard to ovarian hyperstimulation and egg collection procedure ADDIN EN.CITE Venn2001201301172659716122001DecMortality in a cohort of IVF patients2691-6Centre for the Study of Mothers' and Children's Health, La Trobe University, Carlton 3053, Australia. alison.venn@utas.edu.auVenn, A.Hemminki, E.Watson, L.Bruinsma, F.Healy, D.Hum ReprodAdolescentAdultAustralia/epidemiologyCohort StudiesFemaleFertilization in Vitro/*mortalityHumansMiddle AgedOvarian Hyperstimulation Syndrome/mortalityOvulation Induction/mortalityPostpartum PeriodPregnancyhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=11726597[97].
Health outcomes for female patients
The health outcome for patients is anticipated to be similar to that of the IVF procedure, excluding the chance of pregnancy. Most female patients can expect their menstrual cycle to return to normal within six weeks of having the procedure. The hyperstimulated ovary is expected to return to normal size and endocrine pattern within one month of the egg collection procedure. Patient symptoms attributable to fluctuating hormone levels can be anticipated during that time. In addition, there may be symptoms of pelvic discomfort and pain in the immediate post-operative period due to swelling and bleeding that had occurred within the ovary after the egg collection procedure.
In the longer term, studies have looked at the incidence of hormonally related cancers in female patients undertaking the IVF procedure. There is no increased incidence of breast, ovarian or uterine cancer in those patients who have had cycles of ovarian hyperstimulation. The Australian study for breast cancer following ovarian hyperstimulation showed no increased risk for the incidence of breast cancer with five to 15years of follow-up after the treatment was undertaken ADDIN EN.CITE Venn1999201001056067235491901999Nov 6Risk of cancer after use of fertility drugs with in-vitro fertilisation1586-90Centre for the Study of Mothers' and Children's Health, La Trobe University, Carlton, Victoria, Australia. a.venn@latrobe.edu.auVenn, A.Watson, L.Bruinsma, F.Giles, G.Healy, D.LancetAdultAustralia/epidemiologyBreast Neoplasms/*chemically induced/epidemiologyCohort StudiesData Interpretation, StatisticalFemaleFertility Agents/*adverse effectsFertilization in Vitro/*adverse effectsHumansIncidenceInfertility, Female/drug therapyMiddle AgedOvarian Neoplasms/*chemically induced/epidemiologyOvulation Induction/*adverse effectsPopulation SurveillanceRisk FactorsUterine Neoplasms/*chemically induced/epidemiologyhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10560672Venn199520110747559334689811995Oct 14Breast and ovarian cancer incidence after infertility and in vitro fertilisation995-1000Centre for the Study of Mothers' and Children's Health, La Trobe University, Carlton, Victoria, Australia.Venn, A.Watson, L.Lumley, J.Giles, G.King, C.Healy, D.LancetAdultAustralia/epidemiologyBreast Neoplasms/epidemiology/*etiologyCohort StudiesFemaleFertility Agents/*adverse effectsFertilization in Vitro/*adverse effectsFollow-Up StudiesHumansIncidenceInfertility, Female/drug therapyMiddle AgedOvarian Neoplasms/epidemiology/*etiologyOvulation Induction/*adverse effectsRegistrieshttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=7475593Venn200320150127581041722003AprCancer risks associated with the diagnosis of infertility343-67Menzies Centre for Population Health Research, University of Tasmania, 17 Liverpool Street, Hobart, TAS 7000, Australia. alison.venn@utas.edu.auVenn, A.Healy, D.McLachlan, R.Best Pract Res Clin Obstet GynaecolBreast Neoplasms/etiologyChildFemaleFertility Agents, Female/adverse effectsHumansInfertility/*complications/therapyMaleNeoplasms/*etiologyOvarian Neoplasms/etiologyPregnancyPrenatal Exposure Delayed EffectsReproductive Techniques, Assisted/*adverse effectsRisk FactorsTesticular Neoplasms/etiologyhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=12758104[98100].
Exclusion of potential patients based on clinical indicators
Possible exclusion from treatment would be based upon a clinical scenario. This would include:
i. patients in whom the risk of ovarian hyperstimulation would adversely impact the diagnosis, that is, the increased levels of hormone, particularly oestrogen, in women diagnosed with breast cancer. There have been recent reports in the literature of patients having ovarian stimulation with an aromatase inhibitor so as to retrieve oocytes but limit the production of oestrogen from the follicles producing the egg ADDIN EN.CITE Oktay2005210201582441623192005Jul 1Fertility preservation in breast cancer patients: a prospective controlled comparison of ovarian stimulation with tamoxifen and letrozole for embryo cryopreservation4347-53The Center for Reproductive Medicine and Infertility, Department of Obstetrics and Gynecology, Joan and Sanford I. Weill Medical College of Cornell University, 505 E 70th St, HT-340, New York, NY 10021,USA. kuo9001@med.cornell.eduOktay, K.Buyuk, E.Libertella, N.Akar, M.Rosenwaks, Z.J Clin OncolAdultBreast Neoplasms/*therapy*Cryopreservation*Embryo, MammalianFemaleFertility/*drug effectsHumansNitriles/*pharmacologyOvulation Induction/*methodsTamoxifen/*pharmacologyTriazoles/*pharmacologyhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15824416[101].
Whilst the oestrogen level is reduced compared to a normal cycle of ovarian hyperstimulation, there is still the issue of the delay in commencing chemotherapy whilst undergoing ovarian hyperstimulation and oocyte collection. In addition, if there is an over-response to the medication and the ovarian hyperstimulation syndrome develops, then chemotherapy would need to be deferred until the haemo-dynamic situation had resolved
ii. the potential for the initial diagnosis to worsen during the time that it would take to arrange and undertake the procedure of ovarian stimulation and egg harvesting, that is, an aggressive tumour or cancer that could advance in the four to six weeks that may be required to complete the cycle of treatment
iii. patients in whom the procedure of ovarian hyperstimulation may worsen the underlying medical condition, that is, chronic and/or severe renal disease
iv. patients in whom the underlying medical condition would preclude a pregnancy. In medical conditions such as severe pulmonary hypertension, the mortality rate may be in excess of 50 percent if a pregnancy is attempted. However, there would be little point in retrieving the eggs and freezing them for later use in the patient if a pregnancy was absolutely contra-indicated in her, except if a surrogacy arrangement was planned or anticipated.
Damage to the egg
Although the rupture of the cortical granules has been reported following exposure to cryoprotectants ADDIN EN.CITE Schalkoff19895290Schalkoff, M. E.Oskowitz, S. P.Powers, R. D.Ultrastructural observations of human and mouse oocytes treated with cryopreservativesAnimalCryoprotective Agents/*adverse effectsCytoplasmic Granules/drug effects/ultrastructureDimethyl Sulfoxide/adverse effectsFemaleHumanIn VitroMiceOocytes/*drug effects/ultrastructureOrganelles/drug effects/ultrastructurePropylene Glycols/adverse effectsSupport, U.S. Gov't, P.H.S.Biol Reprod1989402379-93Nottola200720700171588182242007AprUltrastructure of human mature oocytes after slow cooling cryopreservation using different sucrose concentrations1123-33Department of Anatomy, University La Sapienza, Rome, Italy. stefania.nottola@uniroma1.itNottola, S. A.Macchiarelli, G.Coticchio, G.Bianchi, S.Cecconi, S.De Santis, L.Scaravelli, G.Flamigni, C.Borini, A.Hum Reprodhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17158818[81, 102], others have reported the converse, that is, a normal population of these granules following freezing ADDIN EN.CITE Sathananthan19875240Sathananthan, A. H.Trounson, A.Freeman, L.Morphology and fertilizability of frozen human oocytesFemale*Fertilization in VitroFreezingHumanMaleOocytes/cytology/*physiology/ultrastructurePreservation, BiologicalSperm-Ovum InteractionsGamete Res1987164343-54Gook19933040Gook, D. A.Osborn, S. M.Johnston, W. I.Cryopreservation of mouse and human oocytes using 1,2-propanediol and the configuration of the meiotic spindleAnimalCell Survival/drug effectsChromosome Abnormalities/chemically inducedCryopreservationCryoprotective Agents/*pharmacologyFemaleHumanMeiosis/*drug effectsMiceMitotic Spindle Apparatus/*drug effectsOocytes/cytology/*drug effectsPropylene Glycols/*pharmacologySupport, Non-U.S. Gov'tHum Reprod1993871101-9[86, 103].
The release of these granules would result in an inability to fertilise, but normal fertilisation following insemination occurred in a similar proportion of frozen to non-frozen eggs ADDIN EN.CITE Gook19943050Gook, D. A.Osborn, S. M.Bourne, H.Johnston, W. I.Fertilization of human oocytes following cryopreservation; normal karyotypes and absence of stray chromosomesCell Survival*Chromosome AberrationsComparative Study*CryopreservationFemale*Fertilization in VitroHuman*KaryotypingMaleOocytes/*physiology/ultrastructureSupport, Non-U.S. Gov'tTime FactorsHum Reprod199494684-91[87]. This study clearly established that cortical granule discharge is not a concern with the current slow-controlled rate freezing of human eggs. Although this has not been specifically assessed following vitrification, the introduction of a sperm directly into the egg (ICSI) would overcome the impact of this damage.
Alterations to other minute structures within the egg involved in moving molecules and energy metabolism are apparent in eggs frozen in the high sucrose (0.3) procedure ADDIN EN.CITE Nottola200720700171588182242007AprUltrastructure of human mature oocytes after slow cooling cryopreservation using different sucrose concentrations1123-33Department of Anatomy, University La Sapienza, Rome, Italy. stefania.nottola@uniroma1.itNottola, S. A.Macchiarelli, G.Coticchio, G.Bianchi, S.Cecconi, S.De Santis, L.Scaravelli, G.Flamigni, C.Borini, A.Hum Reprodhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17158818[102].
Initial studies showed that the spindle that anchors the chromosomes in place dissolved at low temperatures and reformed on subsequent return to body temperature ADDIN EN.CITE Pickering19874940Pickering, S. J.Johnson, M. H.The influence of cooling on the organization of the meiotic spindle of the mouse oocyteAnimalBenzimidazoles/pharmacologyCentriolesChromatin/analysisColdFemaleHistocytochemistry*Meiosis/drug effectsMiceMicrotubules/drug effectsOocytes/*cytology/drug effects*Preservation, BiologicalSupport, Non-U.S. Gov'tTubulin/analysisHum Reprod198723207-16Magistrini19808310Magistrini, M.Szollosi, D.Effects of cold and of isopropyl-N-phenylcarbamate on the second meiotic spindle of mouse oocytesAnimalColdFemaleHerbicides, Carbamate/*pharmacologyIn VitroMeiosis/*drug effectsMiceMicroscopy, ElectronMicrotubules/*drug effects/metabolismMitosis/*drug effectsOocytes/*cytologyOvum/*cytologySupport, Non-U.S. Gov'tEur J Cell Biol1980222699-707[83, 104]. During this process, chromosomes were displaced from the spindle and detected scattered through the egg, which would result in an abnormal chromosome number in the subsequent embryo. This scattering of the chromosomes was only observed in mouse eggs and not observed in human eggs examined under the same conditions ADDIN EN.CITE Pickering1990850Pickering,S.J.Braude,P.R.Johnson,M.H.Cant,A.Currie,J.1990Transient cooling to room temperature can cause irreversible disruption of the meiotic spindle in the human oocyte.Fertil. Steril.54102-108[105].
The addition of the cryoprotectant propanediol protected the spindle during the reduction in temperature both in the mouse ADDIN EN.CITE Van der Elst19885940Van der Elst, J.Van den Abbeel, E.Jacobs, R.Wisse, E.Van Steirteghem, A.Effect of 1,2-propanediol and dimethylsulphoxide on the meiotic spindle of the mouse oocyteAnimalDimethyl Sulfoxide/*pharmacologyFemaleIn VitroMeiosis/drug effectsMiceOocytes/*drug effectsPropylene Glycols/*pharmacologySupport, Non-U.S. Gov'tHum Reprod198838960-7George19932950George, M. A.Johnson, M. H.Cytoskeletal organization and zona sensitivity to digestion by chymotrypsin of frozen-thawed mouse oocytes [see comments]AnimalCell Survival/drug effects*ChymotrypsinCryopreservation/*methodsCytoskeleton/*drug effectsFemaleHeatMetaphase/drug effectsMiceMice, Inbred StrainsMicrofilaments/drug effectsMitotic Spindle Apparatus/drug effectsSupport, Non-U.S. Gov'tZona Pellucida/*drug effectsHum Reprod199384612-20[106, 107] and the human egg ADDIN EN.CITE Gook19933040Gook, D. A.Osborn, S. M.Johnston, W. I.Cryopreservation of mouse and human oocytes using 1,2-propanediol and the configuration of the meiotic spindleAnimalCell Survival/drug effectsChromosome Abnormalities/chemically inducedCryopreservationCryoprotective Agents/*pharmacologyFemaleHumanMeiosis/*drug effectsMiceMitotic Spindle Apparatus/*drug effectsOocytes/cytology/*drug effectsPropylene Glycols/*pharmacologySupport, Non-U.S. Gov'tHum Reprod1993871101-9[86]. In the human egg, no stray chromosomes were detected whether the spindle was abnormal or normal ADDIN EN.CITE Gook19933040Gook, D. A.Osborn, S. M.Johnston, W. I.Cryopreservation of mouse and human oocytes using 1,2-propanediol and the configuration of the meiotic spindleAnimalCell Survival/drug effectsChromosome Abnormalities/chemically inducedCryopreservationCryoprotective Agents/*pharmacologyFemaleHumanMeiosis/*drug effectsMiceMitotic Spindle Apparatus/*drug effectsOocytes/cytology/*drug effectsPropylene Glycols/*pharmacologySupport, Non-U.S. Gov'tHum Reprod1993871101-9[86] after freezing. Further studies showing that human frozen eggs with an abnormal spindle were prohibited from fertilising normally and that normal chromosome numbers were present in those that fertilised ADDIN EN.CITE Gook19943050Gook, D. A.Osborn, S. M.Bourne, H.Johnston, W. I.Fertilization of human oocytes following cryopreservation; normal karyotypes and absence of stray chromosomesCell Survival*Chromosome AberrationsComparative Study*CryopreservationFemale*Fertilization in VitroHuman*KaryotypingMaleOocytes/*physiology/ultrastructureSupport, Non-U.S. Gov'tTime FactorsHum Reprod199494684-91[87] confirmed that this was not a major concern in human eggs but associated specifically with mouse oocytes.
New technology has allowed direct visualisation of the spindle in living eggs and has verified normal spindle reformation after controlled rate freezing in human eggs ADDIN EN.CITE Rienzi200418870149989661932004MarPolscope analysis of meiotic spindle changes in living metaphase II human oocytes during the freezing and thawing procedures655-9Centre for Reproductive Medicine, European Hospital, Via Portuense 700, 00149 Rome, Italy. rienzi.laura@libero.itRienzi, L.Martinez, F.Ubaldi, F.Minasi, M. G.Iacobelli, M.Tesarik, J.Greco, E.Hum Reprodhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=14998966Bianchi200519040157609522042005AprMeiotic spindle imaging in human oocytes frozen with a slow freezing procedure involving high sucrose concentration1078-83Tecnobios Procreazione, Via Dante 15, 40125 Bologna and University of Bologna, 40125 Bologna, Italy.Bianchi, V.Coticchio, G.Fava, L.Flamigni, C.Borini, A.Hum ReprodAdult*CryopreservationCryoprotective AgentsFemale*Fertilization in VitroHumansMeiosis/*physiologyMetaphaseMicroscopy, Confocal/*methodsMitotic Spindle Apparatus/*physiologyOocytes/physiology/*ultrastructureSucrosehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15760952[108, 109].
Assessment of embryos for normal chromosome number detected similar proportions of abnormal chromosomes in both fresh and frozen eggs (~25percent) ADDIN EN.CITE Cobo200118120Use of fluorescence in situ hybridization to assess the chromosomal status of embryos obtained from cryopreserved oocytesCobo, A.Rubio, C.Gerli, S.Ruiz, A.Pellicer, A.Remohi, J.AdultBlastocystChromosome AberrationsChromosomes/*ultrastructureChromosomes, Human, Pair 13Chromosomes, Human, Pair 18Chromosomes, Human, Pair 21*CryopreservationDown SyndromeEmbryo/*ultrastructureFemaleHuman*In Situ Hybridization, FluorescenceMosaicismOocytes/physiology*Preimplantation Diagnosis*Sperm Injections, IntracytoplasmicTrisomyX ChromosomeFertil Steril2001752354-60.[110].
Direct visualisation of eggs after vitrification has also shown the spindle to reform ADDIN EN.CITE Larman200720820180628681562007DecMaintenance of the meiotic spindle during vitrification in human and mouse oocytes692-700Colorado Center for Reproductive Medicine, 799 East Hampden Avenue, Suite 520, Englewood, CO 80113, USA. mlarman@colocrm.comLarman, M. G.Minasi, M. G.Rienzi, L.Gardner, D. K.Reprod Biomed OnlineAnimalsCryopreservation/*methodsCryoprotective Agents/pharmacologyFemaleHumans*MeiosisMiceMice, Inbred C57BLMice, Inbred CBA*Mitotic Spindle ApparatusOocytes/*cytologyTemperaturehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=18062868[111], however no chromosomal assessment has been made of embryos derived from vitrified eggs.
Alterations to the cytoskeleton filaments have been observed after controlled rate freezing procedures and vitrification in some animal eggs ADDIN EN.CITE Vincent1990b6070Vincent, C.Pruliere, G.Pajot-Augy, E.Campion, E.Garnier, V.Renard, J. P.1990bEffects of cryoprotectants on actin filaments during the cryopreservation of one-cell rabbit embryosCryobiology2719-23Actins/*drug effects/metabolism/ultrastructureAnimalCryopreservationCryoprotective Agents/*pharmacologyCytochalasin D/pharmacologyDimethyl Sulfoxide/pharmacologyEmbryo/cytology/*drug effects/metabolismIn VitroMicroscopy, ElectronPolymers/metabolismPropylene Glycols/pharmacologyRabbitsSolvents/pharmacologySupport, Non-U.S. Gov'tVincent19926090Vincent, C.Johnson, M. H.Cooling, cryoprotectants, and the cytoskeleton of the mammalian oocyteAnimal*Cryopreservation/methodsCryoprotective Agents/*adverse effectsCytoskeleton/*drug effectsFemaleHumanMiceMicrofilaments/drug effectsMicrotubules/drug effectsOocytes/*drug effectsSupport, Non-U.S. Gov'tZona Pellucida/drug effects1992Oxf Rev Reprod Biol1473-100Le Gal19944040Le Gal, F.Gasqui, P.Renard, J. P.Differential osmotic behavior of mammalian oocytes before and after maturation: a quantitative analysis using goat oocytes as a modelAnimal*CryopreservationCryoprotective Agents/pharmacokineticsCytochalasin D/pharmacologyFemaleGoatsIn VitroKineticsMicrofilaments/drug effects/ultrastructureModels, BiologicalOocytes/cytology/drug effects/*metabolismOsmosis/*physiologyPermeabilityPropylene Glycols/pharmacokineticsSupport, Non-U.S. Gov'tWater/metabolismCryobiology1994312154-70[82, 112, 113]. These cytoskeleton filaments must function normally for movement of male and female DNA during fertilisation and cleavage. The lack of artificial activation ADDIN EN.CITE Gook19953070Gook, D. A.Schiewe, M. C.Osborn, S. M.Asch, R. H.Jansen, R. P.Johnston, W. I.Intracytoplasmic sperm injection and embryo development of human oocytes cryopreserved using 1,2-propanediolBlastocyst/physiologyCleavage Stage, Ovum*Cryopreservation*Cryoprotective AgentsCytoplasmEmbryo/*growth & developmentFemaleFertilization in Vitro/*methodsHumanMaleMicroinjectionsOocytes/*physiology/ultrastructure*Propylene GlycolsHum Reprod199510102637-41[88] high normal fertilisation ADDIN EN.CITE Gook19943050Gook, D. A.Osborn, S. M.Bourne, H.Johnston, W. I.Fertilization of human oocytes following cryopreservation; normal karyotypes and absence of stray chromosomesCell Survival*Chromosome AberrationsComparative Study*CryopreservationFemale*Fertilization in VitroHuman*KaryotypingMaleOocytes/*physiology/ultrastructureSupport, Non-U.S. Gov'tTime FactorsHum Reprod199494684-91[87] and formation of embryos in the human egg following controlled rate freezing ADDIN EN.CITE Gook19953070Gook, D. A.Schiewe, M. C.Osborn, S. M.Asch, R. H.Jansen, R. P.Johnston, W. I.Intracytoplasmic sperm injection and embryo development of human oocytes cryopreserved using 1,2-propanediolBlastocyst/physiologyCleavage Stage, Ovum*Cryopreservation*Cryoprotective AgentsCytoplasmEmbryo/*growth & developmentFemaleFertilization in Vitro/*methodsHumanMaleMicroinjectionsOocytes/*physiology/ultrastructure*Propylene GlycolsHum Reprod199510102637-41[88] indicate that, if alteration to the cytoskeleton is occurring, it is only transient and not impacting on the subsequent process. Although fertilisation and embryo development occur following vitrification of eggs, studies to dismiss the concerns regarding alteration of the cytoskeleton and artificial activation have not been undertaken at present.
Obstetric outcomes
Egg damage
As explained above, eggs in which the spindle has been damaged are unlikely to proceed through fertilisation. Similarly, damage to the cytoskeleton would prohibit fertilisation and normal embryo development. In both situations, this abnormal material is detected and discarded during the treatment and not transferred to the patient, thereby having no impact on obstetric outcome.
Neonate development
At the recent Second World Congress on Human Oocyte Cryopreservation (2007), an international database aimed at collating outcomes from all forms of egg freezing was initiated. This should provide a systematic reporting of pregnancy, miscarriage and birth data, which does not exist in the present publications.
Unfortunately, at present, there is limited information regarding genetic status or developmental follow-up of babies born from egg freezing, presumably due to the fact that so few babies have been born in any single centre. In the publications mentioned above, very little information is given regarding the pregnancies and/or births apart from an occasional report of term pregnancy, sex of offspring and birthweight.
However a recent abstract attempted to assess outcomes from all publications up to July 2006 ADDIN EN.CITE Tur-Kaspa200720970Tur-Kaspa, I.Gal, M.Horwitz, A.2007Genetics and health of children born from cryopreserved oocytes.Fertility and Sterility88suppl 1.O-37[114]. A similar miscarriage rate to that observed with embryo freezing was reported (~20 percent). Two-thirds of these miscarriages were karyotyped, and all were chromosomally normal. Of the 197 babies born, only one-quarter were subsequently karyotyped; again all were normal. One infant was reported with ventricular septal defect. Health status at birth was reported for two-thirds of the babies and recorded as normal in all, however, subsequent health status at636 months of age was only reported on one-third of infants, but again all were normal.
Two of the larger groups in Italy have also reported outcomes of 165 babies in total ADDIN EN.CITE Borini200720980Borini, A.Cattoli, M.Mazzone, S.Trevisi, M.R.Nalon, M.Iadarola, I.2007Survey of 105 babies born after slow-cooling oocyte cryopreservation.Fertility and Sterility88suppl 1.S13, O-36Levi Setti200720990Levi Setti, P. E.Novara, PCesana, AMorreale, GCriado Scholz, E.Albani, E2007Oocyte cryopreservation from experimental trial to routine clinical application.Fertility and Sterility88suppl 1.S343, P-709[115, 116]. Two women underwent elective abortions, one for trisomy 21 and one for Turners syndrome. Two malformations were detected, one infant with Choanae Atresia and the other with RubinsteinTaybi syndrome, all others were normal.
Another group in the United States reported that 50 babies have been born. Malformations observed were; a set of twins, one born with absence of one ear opening, the other with V.A.T.E.R.; two siblings with autism (these have a naturally conceived sibling with RubinsteinTaybi syndrome); a ventricular septal defect occurred in two children, one has repaired on its own, and the other has required surgical repair (personal communication).
Limited information has been reported with respect to the outcome from vitrified eggs ADDIN EN.CITE Huang200721000Huang, J. Y.Ruvalcaba Castellon, L.A.Garcia Amador, M. I.Lucena, E.Saa, A.Chian, R. C.2007Obstetric and perinatal outcomes in pregnancies conceived by vitrified oocytes in three centers.Fertility and Sterility88suppl 1.S352, P-737[95]. No miscarriage rate, genetic information or health status was given, but no adverse perinatal outcome was reported (173 babies).
Although some of the births from these four studies would have been included in the summary data, the outcomes would not have been included. There is a large amount of literature to review with regard to ongoing development of children born as a result of IVF. Whilst that data shows a slight increase in congenital anomalies in children conceived as a result of IVF, there is no difference between children conceived with a fresh embryo transfer versus a conception after the transfer of frozen embryos. It is possible that the increased incidence of abnormalities is related to the genetic background of the couple on treatment rather than the IVF procedure per se. If that were the case, then a similar profile for early childhood development could be expected in children born as a result of utilising frozen eggs. There will obviously need to be many more children born and followed up before any meaningful conclusions can be drawn.
Maternal outcome
Again no maternal complications have been reported following egg freezing, although miscarriage does occur. Whether the incidence is increased relative to IVF is difficult to ascertain at present. One group, using the altered salt and low sucrose method reported that three out of six pregnancies were lost before 12 weeks gestation ADDIN EN.CITE Quintans200218420Quintans, C JDonaldson, M JBertolino, M VPasqualini, R S2002Birth of two babies using oocytes that were cryopreserved in a choline-based freezing medium.Human Reproduction17123149-3152[54]. However, a number of other studies using controlled rate freezing ADDIN EN.CITE Borini200419250153747028232004SepPregnancies and births after oocyte cryopreservation601-5Tecnobios Procreazione, Via Dante 15, 40125 Bologna, Italy. borini@tecnobios.itBorini, A.Bonu, M. A.Coticchio, G.Bianchi, V.Cattoli, M.Flamigni, C.Fertil SterilCell Survival*Cryopreservation/methodsEmbryo ImplantationFemaleHumansOocytes/*cytology*PregnancyRetrospective Studies*Sperm Injections, Intracytoplasmichttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15374702Borini2006b19190Borini, A.Sciajno,R.Bianchi, V.Sereni,EFlamigni, C.Coticchio, G.2006bCinical outcome of oocyte cryopreservation after slow cooling with a protocol utilizing a high sucrose concentrationHuman Reproduction212512-517Bianchi200719990172073331412007JanDifferential sucrose concentration during dehydration (0.2 mol/l) and rehydration (0.3 mol/l) increases the implantation rate of frozen human oocytes64-71Tecnobios Procreazione, Via Dante 15, 40125 Bologna, Italy.Bianchi, V.Coticchio, G.Distratis, V.Di Giusto, N.Flamigni, C.Borini, A.Reprod Biomed Onlinehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17207333Konc200719790172073241412007JanDoes oocyte cryopreservation have a future in Hungary?11-3Infertility and IVF Centre of Buda, Saint Janos Hospital, Budapest 1125, Hungary.Konc, J.Kanyo, K.Cseh, S.Reprod Biomed Onlinehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17207324Lappi200720870Lappi, M.Magli, M.C.Gianaroli, L.Resta, S.Capoti, A.Borghi, E.Ferraretti, A.P.2007Factors affecting the outcome of oocyte freezingHuman Reproduction22suppl 1.i156, P-398[15, 42, 50, 63, 91] and one using vitrification ADDIN EN.CITE Cobo200720940178898652007Sep 21Comparison of concomitant outcome achieved with fresh and cryopreserved donor oocytes vitrified by the Cryotop methodIVI Universidad de Valencia, Valencia, Spain.Cobo, A.Kuwayama, M.Perez, S.Ruiz, A.Pellicer, A.Remohi, J.Fertil Sterilhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17889865[80] have reported 2025 percent miscarriage rates. Although more numbers are needed to make a meaningful comparison, these latter rates do not appear to be significantly different from those associated with embryo freezing. No adverse obstetric outcomes have been reported. The mean gestational age at delivery for vitrification and the controlled rate freezing procedure for singleton births was 37 ADDIN EN.CITE Huang200721000Huang, J. Y.Ruvalcaba Castellon, L.A.Garcia Amador, M. I.Lucena, E.Saa, A.Chian, R. C.2007Obstetric and perinatal outcomes in pregnancies conceived by vitrified oocytes in three centers.Fertility and Sterility88suppl 1.S352, P-737[95] and 39 weeks ADDIN EN.CITE Borini200720980Borini, A.Cattoli, M.Mazzone, S.Trevisi, M.R.Nalon, M.Iadarola, I.2007Survey of 105 babies born after slow-cooling oocyte cryopreservation.Fertility and Sterility88suppl 1.S13, O-36[115] respectively, and for multiple births 36 weeks. Mean birthweight was slightly lower with vitrification (singleton 2.9 kilograms and multiple 2.2 kilograms) relative to the controlled rate freezing procedure (3.3 and 2.6 kilograms respectively), but this needs to be compared to age and ethnic population matched data.
Delay of other treatments
Patients requiring egg freezing to preserve their fertility may need to delay other treatments such as chemotherapy until eggs have been collected. In those cases in which this is not advised following consultation with other medical specialists, the alternative procedure of freezing ovarian tissue could be offered to eliminate the delay.
Age range
In most clinical studies reported above, the majority of the patients are less than 38years of age. The application of egg freezing to older patients with, on average, lower numbers of eggs following ovarian stimulation, together with lower implantation rates and a higher risk of chromosomal abnormalities is not advisable. Ovarian tissue has been collected and frozen from young children (two years of age) ADDIN EN.CITE Poirot200217970Human ovarian tissue cryopreservation: indications and feasibilityPoirot, C.Vacher-Lavenu, M. C.Helardot, P.Guibert, J.Brugieres, L.Jouannet, P.Hum Reprod20021761447-52.[117] and, at Melbourne IVF, as young as four months old.
Risk of other disease
There has been no report of any other diseases that has resulted or occurred following egg freezing. It would be expected that the risk associated with egg freezing would be similar to that with IVF. No evidence was found when reviewing the available literature that the use of frozen eggs increased the risks of other diseases such as cancer.
Animal studies
Species
The major species studied have been the mouse, rabbit, cattle and pig. There are a number of limitations with summarising the animal data:
1. Although often the cryoprotectant used is the same, the procedure varies between studies for the same species.
2. Variation in the egg size and the rate at which water moves between species indicate that a procedure that gives high results in one species may not be appropriate in different species.
3. In domestic species the eggs used are at a different stage of development and are either frozen at this stage or matured in culture (IVM) before freezing. Eggs collected at this immature stage appear to be compromised in their ability to form a normal spindle, to undergo normal fertilisation and produce embryos, which are often of poor quality.
In contrast to the human studies, in the animal studies, vitrification is used in preference to controlled rate freezing. Also development to the foetal stage and beyond has only been assessed in mice.
Numbers and efficacy of using frozen eggs
Mouse
An example of the impact of minor technical variation is reported using two types of containers in which the eggs are frozen (n = 338) with one type resulting in a higher survival (80 percent compared to 60 percent). However, fewer normal spindles were present (21 percent compared to 78 percent) ADDIN EN.CITE Chen2000198901109803315122000DecOpen pulled straws for vitrification of mature mouse oocytes preserve patterns of meiotic spindles and chromosomes better than conventional straws2598-603Department of Obstetrics and Gynecology, College of Medicine and the Hospital, National Taiwan University, Taipei, Taiwan.Chen, S. U.Lien, Y. R.Chen, H. F.Chao, K. H.Ho, H. N.Yang, Y. S.Hum ReprodAnimalsChromosomes/*ultrastructureCryopreservation/*instrumentation/*methodsCryoprotective AgentsCytoskeleton/*ultrastructureFemale*MeiosisMiceMicrotubules/ultrastructureOocytes/physiology/*ultrastructurehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=11098033[118]. In another study comparing freezing eggs by the controlled rate freezing procedure (240) and vitrification (170), both using the same cryoprotectant (DMSO), the survival rate was better with vitrification relative to controlled rate (94 percent versus 69 percent) and more eggs were obtained with a normal spindle following vitrification (87 percent versus 72 percent for controlled rate freezing) ADDIN EN.CITE Aigner1992199101500486761992JulThe influence of slow and ultra-rapid freezing on the organization of the meiotic spindle of the mouse oocyte857-64Division of Gynaecological Endocrinology and Reproductive Medicine, University of Erlangen, FRG.Aigner, S.Van der Elst, J.Siebzehnrubl, E.Wildt, L.Lang, N.Van Steirteghem, A. C.Hum ReprodAnimalsChromosomes/*ultrastructureCryopreservation/*methodsDimethyl SulfoxideFemale*FreezingImmunohistochemistryKinetics*MeiosisMiceMice, Inbred C57BLMice, Inbred CBAMicrotubules/ultrastructureOocytes/*ultrastructureTime Factorshttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=1500486[119].
A similar result was observed with controlled rate freezing of 1837 mouse eggs, whether using the cryoprotectant DMSO or the one use for human controlled rate freezing (propanediol). Both resulted in similar survival (60 percent) and fertilisation (50 percent) ADDIN EN.CITE Todorow1989a5770Todorow, S. J.Siebzehnrubl, E. R.Koch, R.Wildt, L.Lang, N.1989aComparative results on survival of human and animal eggs using different cryoprotectants and freeze-thawing regimens. I. Mouse and hamsterHum Reprod47805-11AnimalCase ReportCell Survival*CryopreservationCryoprotective Agents/*pharmacologyDimethyl Sulfoxide/pharmacologyEmbryo TransferFemaleFertilization in Vitro/methodsFreezingHamstersMice*OocytesPropylene Glycols/pharmacologySupport, Non-U.S. Gov'tTemperature[120].
Subsequent development following vitrification using the cryoprotectant used for human vitrification (EG) in over 2600 eggs resulted in an average survival of 70percent, half of which fertilised (50percent), and just over half of these developed to the implantation stage embryo (60 percent). Following transfer of these, half continued to foetal development.
Unfortunately the study was not continued to live births, and no distinction was made between normal and abnormal developing foetuses. However, using this procedure, 20foetuses resulted from 100 vitrified eggs compared to 48 per 100 fresh eggs ADDIN EN.CITE Rayos199419920818257910011994JanQuick freezing of unfertilized mouse oocytes using ethylene glycol with sucrose or trehalose123-9Department of Theriogenology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.Rayos, A. A.Takahashi, Y.Hishinuma, M.Kanagawa, H.J Reprod FertilAnimalsCryopreservation/*methods*Ethylene GlycolsFemaleFertilization in VitroMiceMice, Inbred Strains*OocytesSucroseTime FactorsTrehalosehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=8182579[121].
Vitrification of 260 mouse eggs using a similar method resulted in 97 percent survival, of which 70 percent fertilised and half of these grew to the implantation stage of development and, following transfer, 10 percent resulted in live pups. This corresponds to three births per 100frozen eggs, which is half the number for fresh eggs ADDIN EN.CITE Aono2005199701620999684 Suppl 22005OctProduction of live offspring from mouse germinal vesicle-stage oocytes vitrified by a modified stepwise method, SWEID1078-82Yoshida Lady's Clinic, Sendai. ylc4@sirius.ocn.ne.jpAono, N.Abe, Y.Hara, K.Sasada, H.Sato, E.Yoshida, H.Fertil SterilAnimalsCryopreservation/*methodsFemaleHumans*Live BirthMaleMiceMice, Inbred C57BLMice, Inbred CBAOocytes/*cytology/*growth & developmenthttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16209996[122].
Foetal development or live births have been reported following freezing in a number of early studies. The methods used for freezing in these have since been improved, but very few of the recent studies continue development through to the foetal stage. In one of the early studies, over 500 mouse eggs were frozen using DMSO and controlled rate freezing (no rate for survival was reported); 36percent fertilised, 67 percent implanted and half of these developed to live foetuses ADDIN EN.CITE Glenister19872980Glenister, P. H.Wood, M. J.Kirby, C.Whittingham, D. G.Incidence of chromosome anomalies in first-cleavage mouse embryos obtained from frozen-thawed oocytes fertilized in vitroAneuploidyAnimalChromosome Abnormalities/*etiologyCleavage Stage, Ovum/*physiologyDimethyl Sulfoxide/pharmacologyEmbryo TransferFertilization in Vitro/*methodsMiceOocytes/*physiology*Preservation, BiologicalGamete Res1987163205-16[123]. Another study reported that, following the freezing of over 900mouse eggs, 37 foetuses developed and 24 live pups were born (three live births per 100 frozen eggs) ADDIN EN.CITE Whittingham19776200Whittingham, D. G.Fertilization in vitro and development to term of unfertilized mouse oocytes previously stored at --196 degrees CAnimalBlastocyst/transplantationCell SurvivalFemale*Fertilization/drug effectsFreezingHybridizationIn VitroMiceOocytes/*physiology/transplantationOvum/*physiologyPregnancyTransplantation, HomologousJ Reprod Fertil197749189-94[124]. In a comparison of vitrification and controlled rate freezing 37 live pups were born from 1700 vitrified eggs and 46 pups from 745frozen eggs (two per 100 vitrified and six per 100 frozen eggs) ADDIN EN.CITE Kola19883970Kola, I.Kirby, C.Shaw, J.Davey, A.Trounson, A.Vitrification of mouse oocytes results in aneuploid zygotes and malformed fetusesAbnormalities/*etiology*AneuploidyAnimalDisease Models, AnimalEmbryo TransferFemaleFertilization in VitroFreezingMaleMiceOocytes/*cytologyReference ValuesSupport, Non-U.S. Gov'tZygote/*cytologyTeratology1988385467-74[125].
Rabbit
Applying this vitrification procedure with slight modifications to1758 rabbit eggs also resulted in a high survival rate (80percent). However, only one-third of the eggs contained a normal spindle, which translated into a poor fertilisation rate of less than 10percent, and less than half of those subsequently formed embryos ADDIN EN.CITE Cai200519870159329102072005JulCryoloop vitrification of rabbit oocytes1969-74Department of Obstetrics and Gynaecology, Third Hospital, Peking University, Peking, China 100083.Cai, X. Y.Chen, G. A.Lian, Y.Zheng, X. Y.Peng, H. M.Hum ReprodAnimalsChromosomes/ultrastructureCryopreservation/*methodsCryoprotective AgentsDimethyl SulfoxideEmbryonic DevelopmentEthylene GlycolFemaleHumansMetaphaseMicrotubules/ultrastructureMitotic Spindle Apparatus/ultrastructure*Oocytes/cytologyRabbitsSperm Injections, Intracytoplasmichttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15932910[126]. Overall, only two eggs out of 100 vitrified resulted in an embryo compared to 53 embryos from 100fresh eggs.
Cattle
A study using a large number of cattle immature eggs that were matured (IVM) prior to vitrification (over 1000) achieved slightly better results ADDIN EN.CITE Chian200419880156476215062004DecHigh survival rate of bovine oocytes matured in vitro following vitrification685-96Division of Reproductive Biology, Department of Obstetrics and Gynecology, McGill University, Montreal, Canada. ri-cheng.chian@muhc.mcgill.caChian, R. C.Kuwayama, M.Tan, L.Tan, J.Kato, O.Nagai, T.J Reprod DevAnimalsBlastocyst/metabolismCattleCell Culture Techniques/*methodsCell SurvivalCryoprotective Agents/pharmacologyDimethyl Sulfoxide/chemistryEmbryo/cytologyEmbryo Culture Techniques/*methodsEthylene Glycol/chemistryFemaleFertilization in Vitro/methodsOocytes/*cytology/*metabolismOvary/metabolismPropylene Glycols/chemistrySucrose/chemistryhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15647621[127]. Survival was consistently greater than 90 percent, however, only half of these fertilised and formed embryos, resulting in only three out of 100 eggs frozen continuing to cleave up to the implantation stage, in contrast to 25 per 100 fresh eggs. Again a slight modification and the use of a different freezing container resulted in lower survival (60 percent), but a higher proportion cleaved to the implantation stage 10 per 100 frozen eggs ADDIN EN.CITE Martino19961993087226275451996MayDevelopment into blastocysts of bovine oocytes cryopreserved by ultra-rapid cooling1059-69Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Canada.Martino, A.Songsasen, N.Leibo, S. P.Biol ReprodAnimalsBlastocyst/*physiologyCattle/*embryologyCryopreservation/*methodsCulture TechniquesFemaleFertilization in VitroFixativesOocytes/*physiologyTime FactorsZygote/physiologyhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=8722627[128].
Pig
Two studies of 682 pig IVM eggs using a similar vitrification procedure to those above resulted in survival of 60 percent of eggs, however, none of these subsequently developed to the implantation stage of development. In contrast, 27 fresh eggs formed these embryo from 100 fresh eggs ADDIN EN.CITE Shi2006199401659573013142006AprImproved development by Taxol pretreatment after vitrification of in vitro matured porcine oocytes795-804Laboratory of Animal Embryonic Biotechnology, College of Animal Science, China Agricultural University; No. 2 Yuanmingyuan West Road, Haidian District, Beijing 100094, PR China.Shi, W. Q.Zhu, S. E.Zhang, D.Wang, W. H.Tang, G. L.Hou, Y. P.Tian, S. J.ReproductionAnimalsCell SurvivalCells, CulturedChromosomes/ultrastructureColoring AgentsCryopreservation/*methodsEmbryonic DevelopmentFemaleFluoresceinsMicroscopy, ConfocalMicrotubules/ultrastructure*Oocytes/ultrastructure*OogenesisPaclitaxel/*pharmacologyParthenogenesisRewarming*Swinehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16595730Wu2006199501689455373112006NovEffects of cryopreservation on the developmental competence, ultrastructure and cytoskeletal structure of porcine oocytes1454-62College of Veterinary Medicine, Nanjing Agricultural University, Jiangsu, China.Wu, C.Rui, R.Dai, J.Zhang, C.Ju, S.Xie, B.Lu, X.Zheng, X.Mol Reprod DevAnimals*CryopreservationCytoskeleton/ultrastructureFemaleMeiosisOocytes/*physiology/*ultrastructureSus scrofa/*physiology*Tissue Preservationhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16894553[129, 130].
Risks using frozen eggs
Spindle damage
As stated above, studies involving freezing of animal eggs often assess the spindle and normal configuration of the chromosomes. Damage to these appears more common in eggs that have been collected at the immature stage and frozen at this stage or following maturation. In pig eggs, following vitrification, only 10percent of the eggs had a normal spindle and, in over 60percent of the eggs, the chromosomes were either dispersed throughout the egg or not detected ADDIN EN.CITE Wu2006199501689455373112006NovEffects of cryopreservation on the developmental competence, ultrastructure and cytoskeletal structure of porcine oocytes1454-62College of Veterinary Medicine, Nanjing Agricultural University, Jiangsu, China.Wu, C.Rui, R.Dai, J.Zhang, C.Ju, S.Xie, B.Lu, X.Zheng, X.Mol Reprod DevAnimals*CryopreservationCytoskeleton/ultrastructureFemaleMeiosisOocytes/*physiology/*ultrastructureSus scrofa/*physiology*Tissue Preservationhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16894553[130]. This level of damage to the spindle was confirmed by another study of vitrified pig eggs, but chromosomes were retained on the spindle in more of the eggs (60 percent) ADDIN EN.CITE Shi2006199401659573013142006AprImproved development by Taxol pretreatment after vitrification of in vitro matured porcine oocytes795-804Laboratory of Animal Embryonic Biotechnology, College of Animal Science, China Agricultural University; No. 2 Yuanmingyuan West Road, Haidian District, Beijing 100094, PR China.Shi, W. Q.Zhu, S. E.Zhang, D.Wang, W. H.Tang, G. L.Hou, Y. P.Tian, S. J.ReproductionAnimalsCell SurvivalCells, CulturedChromosomes/ultrastructureColoring AgentsCryopreservation/*methodsEmbryonic DevelopmentFemaleFluoresceinsMicroscopy, ConfocalMicrotubules/ultrastructure*Oocytes/ultrastructure*OogenesisPaclitaxel/*pharmacologyParthenogenesisRewarming*Swinehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=16595730[129].
Controlled rate freezing of IVM cattle eggs resulted in a similar rate of both spindle damage and normal chromosome appearance ADDIN EN.CITE Saunders199919960103770476111999JulEffects of cryopreservation procedures on the cytology and fertilization rate of in vitro-matured bovine oocytes178-87Department of Animal Science, Cornell University, Ithaca, New York 14850, USA.Saunders, K. M.Parks, J. E.Biol ReprodActins/analysisAnimals*CattleChromosomes/ultrastructure*Cryopreservation/*methodsCytoskeleton/chemistryEthylene Glycol/pharmacologyFemale*Fertilization in VitroFreezingHeatMicrofilaments/ultrastructureMicrotubules/ultrastructureOocytes/*physiology/*ultrastructurehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10377047[131]. Care must be taken in interpreting these results; this damage does not appear to be specific to the mechanism of freezing but is probably due to the reduced temperature and/or the cryoprotectant together with the immature nature of the egg. In all of these studies, a correspondingly low proportion of the eggs continued to develop through fertilisation and cleavage.
In contrast, 70 percent of mouse eggs following the controlled rate freezing procedure and 80 percent following vitrification had normal spindles ADDIN EN.CITE Aigner1992199101500486761992JulThe influence of slow and ultra-rapid freezing on the organization of the meiotic spindle of the mouse oocyte857-64Division of Gynaecological Endocrinology and Reproductive Medicine, University of Erlangen, FRG.Aigner, S.Van der Elst, J.Siebzehnrubl, E.Wildt, L.Lang, N.Van Steirteghem, A. C.Hum ReprodAnimalsChromosomes/*ultrastructureCryopreservation/*methodsDimethyl SulfoxideFemale*FreezingImmunohistochemistryKinetics*MeiosisMiceMice, Inbred C57BLMice, Inbred CBAMicrotubules/ultrastructureOocytes/*ultrastructureTime Factorshttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=1500486[119]. Another study has confirmed this high proportion with normal spindle after vitrification (80percent). However, the same procedure in a different container resulted in only 20 percent normal ADDIN EN.CITE Chen2000198901109803315122000DecOpen pulled straws for vitrification of mature mouse oocytes preserve patterns of meiotic spindles and chromosomes better than conventional straws2598-603Department of Obstetrics and Gynecology, College of Medicine and the Hospital, National Taiwan University, Taipei, Taiwan.Chen, S. U.Lien, Y. R.Chen, H. F.Chao, K. H.Ho, H. N.Yang, Y. S.Hum ReprodAnimalsChromosomes/*ultrastructureCryopreservation/*instrumentation/*methodsCryoprotective AgentsCytoskeleton/*ultrastructureFemale*MeiosisMiceMicrotubules/ultrastructureOocytes/physiology/*ultrastructurehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=11098033[118]. Both of these studies showed that time is required after thawing for the spindle to regain its normal appearance.
This is the likely reason for the observation of a high proportion of eggs with an abnormal spindle after exposure to a reduced temperature reported in earlier studies ADDIN EN.CITE Magistrini19808310Magistrini, M.Szollosi, D.Effects of cold and of isopropyl-N-phenylcarbamate on the second meiotic spindle of mouse oocytesAnimalColdFemaleHerbicides, Carbamate/*pharmacologyIn VitroMeiosis/*drug effectsMiceMicroscopy, ElectronMicrotubules/*drug effects/metabolismMitosis/*drug effectsOocytes/*cytologyOvum/*cytologySupport, Non-U.S. Gov'tEur J Cell Biol1980222699-707Pickering19874940Pickering, S. J.Johnson, M. H.The influence of cooling on the organization of the meiotic spindle of the mouse oocyteAnimalBenzimidazoles/pharmacologyCentriolesChromatin/analysisColdFemaleHistocytochemistry*Meiosis/drug effectsMiceMicrotubules/drug effectsOocytes/*cytology/drug effects*Preservation, BiologicalSupport, Non-U.S. Gov'tTubulin/analysisHum Reprod198723207-16Johnson19873810Johnson, M. H.Pickering, S. J.The effect of dimethylsulphoxide on the microtubular system of the mouse oocyteAnimalAntitubercular Agents/pharmacologyBenzimidazoles/pharmacologyChromatin/metabolismCytochalasins/pharmacologyDimethyl Sulfoxide/*pharmacologyFemaleMiceMicrotubules/*drug effectsOocytes/*drug effectsSupport, Non-U.S. Gov'tTubulin/metabolismDevelopment19871002313-24Pickering1990850Pickering,S.J.Braude,P.R.Johnson,M.H.Cant,A.Currie,J.1990Transient cooling to room temperature can cause irreversible disruption of the meiotic spindle in the human oocyte.Fertil. Steril.54102-108Sathananthan19925270Sathananthan, A. H.Kirby, C.Trounson, A.Philipatos, D.Shaw, J.The effects of cooling mouse oocytesAnimalChromosome Aberrations*ColdComparative StudyCryopreservationFreezingHumanMeiosisMiceMice, Inbred CBAMice, Inbred C57BLMicroscopy, ElectronMicrotubules/ultrastructureMitotic Spindle Apparatus/ultrastructure*Oocytes/ultrastructureOrganelles/ultrastructureSingle-Blind MethodSpecies SpecificitySupport, Non-U.S. Gov'tJ Assist Reprod Genet199292139-48[83, 104, 105, 132, 133].
In all of these comparative studies between controlled rate freezing and vitrification, there is a delay of around one hour at 22C before returning to the temperature at which the spindle reforms (37C) in the controlled rate studies but not in vitrification. These differences may be eliminated by maintaining the temperature at 37C during the dehydration and rehydration steps for the controlled rate freezing, which has been the aim of the 0.2M sucrose procedure used for human eggs. Similarly cytoskeleton filaments require time and the appropriate temperature to regain normality following freezing and thawing ADDIN EN.CITE Aigner1992199101500486761992JulThe influence of slow and ultra-rapid freezing on the organization of the meiotic spindle of the mouse oocyte857-64Division of Gynaecological Endocrinology and Reproductive Medicine, University of Erlangen, FRG.Aigner, S.Van der Elst, J.Siebzehnrubl, E.Wildt, L.Lang, N.Van Steirteghem, A. C.Hum ReprodAnimalsChromosomes/*ultrastructureCryopreservation/*methodsDimethyl SulfoxideFemale*FreezingImmunohistochemistryKinetics*MeiosisMiceMice, Inbred C57BLMice, Inbred CBAMicrotubules/ultrastructureOocytes/*ultrastructureTime Factorshttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=1500486[119].
Chromosomal abnormalities
The disruption of the spindle following freezing may result in eggs with abnormal chromosome distribution. However, the rate of aneuploidy (which would be expected to be higher due to more abnormal spindles following controlled rate freezing) was observed to be the same in all conditions (9percent) ADDIN EN.CITE Huang20072084017544423884 Suppl2007OctEffect of choline-supplemented sodium-depleted slow freezing versus vitrification on mouse oocyte meiotic spindles and chromosome abnormalities1093-100Division of Reproductive Biology and Experimental Medicine, Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec, Canada.Huang, J. Y.Chen, H. Y.Tan, S. L.Chian, R. C.Fertil SterilAnimalsCholine/*administration & dosage*Chromosome Aberrations/embryologyCryopreservation/*methodsFemaleFreezingMaleMeiosis/drug effects/*physiologyMice*OocytesSodium/*administration & dosage/metabolismTime Factorshttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17544423[134]. It is, however, unlikely that these eggs would subsequently fertilise and form normal embryos considering the above data. Two studies assessing the embryos formed following freezing or exposure to 0C reported a similar level of chromosomal abnormalities in embryos from fresh or frozen eggs (1.5percent) ADDIN EN.CITE Glenister19872980Glenister, P. H.Wood, M. J.Kirby, C.Whittingham, D. G.Incidence of chromosome anomalies in first-cleavage mouse embryos obtained from frozen-thawed oocytes fertilized in vitroAneuploidyAnimalChromosome Abnormalities/*etiologyCleavage Stage, Ovum/*physiologyDimethyl Sulfoxide/pharmacologyEmbryo TransferFertilization in Vitro/*methodsMiceOocytes/*physiology*Preservation, BiologicalGamete Res1987163205-16Van der Elst19885940Van der Elst, J.Van den Abbeel, E.Jacobs, R.Wisse, E.Van Steirteghem, A.Effect of 1,2-propanediol and dimethylsulphoxide on the meiotic spindle of the mouse oocyteAnimalDimethyl Sulfoxide/*pharmacologyFemaleIn VitroMeiosis/drug effectsMiceOocytes/*drug effectsPropylene Glycols/*pharmacologySupport, Non-U.S. Gov'tHum Reprod198838960-7[106, 123]. Using the same freezing procedure another study showed a three-fold increase in chromosomal abnormalities in embryos derived from frozen mouse eggs (fresh: 12 percent compared with frozen: 32 percent) ADDIN EN.CITE Kola19883970Kola, I.Kirby, C.Shaw, J.Davey, A.Trounson, A.Vitrification of mouse oocytes results in aneuploid zygotes and malformed fetusesAbnormalities/*etiology*AneuploidyAnimalDisease Models, AnimalEmbryo TransferFemaleFertilization in VitroFreezingMaleMiceOocytes/*cytologyReference ValuesSupport, Non-U.S. Gov'tZygote/*cytologyTeratology1988385467-74[125]. Eggs were also vitrified in this study, and 38percent of the embryos that developed were chromosomal abnormal.
On subsequent assessment of the foetuses that developed following vitrification four abnormal foetuses (one anencephaly, three hydrocephalies) were detected, and none were observed in either the fresh or controlled rate freezing group.
Development
Metabolism in mouse eggs has been shown to be reduced following both types of freezing but to a lesser extent following vitrification than controlled rate freezing ADDIN EN.CITE Lane200121010111702765832001MarVitrification of mouse oocytes using a nylon loop342-7Colorado Center for Reproductive Medicine, Research and Development, Englewood, Colorado 80110, USA. mlane@colocrm.comLane, M.Gardner, D. K.Mol Reprod DevAnimalsBlastocyst/*physiology*Cell SurvivalCryopreservation/*methodsCulture TechniquesDiphenhydramine/analogs & derivativesFemaleFertilization in VitroHumansMaleMiceMice, Inbred C57BLMice, Inbred CBAOocytes/*physiologyRandom Allocationhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=11170276[135]. The proteins present within mouse eggs may also be altered after freezing ADDIN EN.CITE Gardner200720690170495896712007Jan 1Analysis of oocyte physiology to improve cryopreservation procedures64-72Colorado Center for Reproductive Medicine, Englewood, CO 80113, USA. dgardner@colocrm.comGardner, D. K.Sheehan, C. B.Rienzi, L.Katz-Jaffe, M.Larman, M. G.Theriogenologyhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17049589[136].
Again, these changes may relate to the temperature eggs are exposed to during thawing, and whether either of these impact on subsequent development is unknown.
There have been no reports of any potential side effects from the freezing of eggs in any animal.
No ongoing development of offspring has been reported using frozen eggs in any animal species.
General
Alternative procedures
An alternative procedure to freezing mature eggs is to freeze the eggs at a very young stage embedded within the ovarian tissue ADDIN EN.CITE Poirot200217970Human ovarian tissue cryopreservation: indications and feasibilityPoirot, C.Vacher-Lavenu, M. C.Helardot, P.Guibert, J.Brugieres, L.Jouannet, P.Hum Reprod20021761447-52.Gook19993100Gook, D. A.Edgar, D. H.Stern, C.1999Effect of cooling rate and dehydration regimen on the histological appearance of human ovarian cortex following cryopreservation in 1, 2- propanediolHum Reprod1482061-8AdolescenceAdult*CryopreservationFemaleFertilization in VitroHuman*Oocytes*Ovary*Propylene GlycolWaterhttp://www.ncbi.nlm.nih.gov/cgi-bin/Entrez/referer?http://humrep.oupjournals.org/cgi/content/full/14/8/2061[117, 137] as discussed above.
This procedure requires no preparation of the tissue (no need for hormones before collecting the tissue). This technology is generally used in the situation where the patient urgently requires chemotherapy or radiotherapy, and there is no time to undergo an ovarian stimulation cycle to collect mature eggs. A similar risk would be associated with obtaining the ovarian tissue to freeze and freezing mature eggs. Due to their specific medical condition, some of these patients will be at greater risk during and following either procedure.
Concluding remarks
The review of animal studies using frozen eggs has highlighted the difficulties associated with using an animal model to develop freezing technology for the human egg. The mouse egg, which was originally used and associated with much of the damage reported with egg freezing, is a completely inappropriate model for the human egg. Studies with human mature eggs have indicated that this damage is generally reversible and subsequent development from damaged human eggs is unlikely. Although there is variability amongst procedures used for human egg freezing, there are now a large number of eggs frozen (16,000) and a reasonable number of births (220) to suggest that there is no elevated risk associated with freezing human eggs. Obviously, a follow-up study on the development of children from egg freezing is required to confirm this.
While initial reports suggested that egg freezing may be significantly less efficient than embryo freezing, recent improvements appear to offer more promise. At present, the results are compromised by the lack of data comparing egg freezing to embryo freezing within the same clinic; which is required to overcome the variation that exists between units, reported in the results from many forms of assisted reproductive technology.
Recent improvements in embryo culture methods would also be expected to improve the overall outcome from egg freezing.
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78. Wu J, Zhang L, Wang X. 2001. In vitro maturation, fertilization and embryo development after ultrarapid freezing of immature human oocytes. Human Reproduction 121: 38993.
79. Yoon TK, et al. 2007. Survival rate of human oocytes and pregnancy outcome after vitrification using slush nitrogen in assisted reproductive technologies. Fertility and Sterility 88(4): 9526.
80. Cobo A, et al. 2007. Comparison of concomitant outcome achieved with fresh and cryopreserved donor oocytes vitrified by the Cryotop method. Fertility and Sterility.
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87. Gook DA, et al. 1994. Fertilization of human oocytes following cryopreservation; normal karyotypes and absence of stray chromosomes. Human Reproduction 9(4): 68491.
88. Gook DA, et al. 1995. Intracytoplasmic sperm injection and embryo development of human oocytes cryopreserved using 1,2-propanediol. Human Reproduction 10(10): 263741.
89. Porcu E, et al. 1998. Birth of six healthy children after intracytoplasmic sperm injection of cryopreserved human oocytes. Human Reproduction 13: 124. Abst O-240, 14th Annual ESHRE Meeting.
90. Tucker MJ, et al. 1998. Birth after cryopreservation of immature oocytes with subsequent in vitro maturation. Fertility and Sterility 70(3): 5789.
91. Borini A, et al. 2004. Pregnancies and births after oocyte cryopreservation. Fertility and Sterility 82(3): 6015.
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93. Yang D, et al. 1998. A twin pregnancy after microinjection of human cryopreserved oocyte with a specially developed oocyte cryopreservation regime. Fertility and Sterility 70 (3,Suppl1): S239, Abst P-357.
94. Kyono K, et al. 2001. Pregnancy and delivery of a healthy female infant after intracytoplasmic sperm injection into cryopreserved human oocytes. Fertility and Sterility 46:1717.
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96. Sher G, et al. 2007. Selective vitrification of euploid oocytes markedly improves their post-warming viability and post-fertilization pregnancy generating potential ,thereby opening the door to commercial egg banking. Fertility and Sterility 88 (Suppl 1): S343, P-711.
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99. Venn A, et al. 1995. Breast and ovarian cancer incidence after infertility and in vitro fertilisation. Lancet 346(8981): 9951000.
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101. Oktay K, et al. 2005. Fertility preservation in breast cancer patients: a prospective controlled comparison of ovarian stimulation with tamoxifen and letrozole for embryo cryopreservation. Journal of Clinical Oncology 23(19): 434753.
102. Nottola SA, et al. 2007. Ultrastructure of human mature oocytes after slow cooling cryopreservation using different sucrose concentrations. Human Reproduction 22(4):112333.
103. Sathananthan AH, Trounson A, Freeman L. 1987. Morphology and fertilizability of frozen human oocytes. Gamete Research 16(4): 34354.
104. Magistrini M, Szollosi D. 1980. Effects of cold and of isopropyl-N-phenylcarbamate on the second meiotic spindle of mouse oocytes. European Journal of Cellular Biology 22(2):699707.
105. Pickering SJ, et al. 1990. Transient cooling to room temperature can cause irreversible disruption of the meiotic spindle in the human oocyte. Fertility and Sterility 54: 1028.
106. Van der Elst J, et al. 1988. Effect of 1,2-propanediol and dimethylsulphoxide on the meiotic spindle of the mouse oocyte. Human Reproduction 3(8): 9607.
107. George MA, Johnson MH. 1993. Cytoskeletal organization and zona sensitivity to digestion by chymotrypsin of frozen-thawed mouse oocytes [see comments]. Human Reproduction 8(4): 61220.
108. Rienzi L, et al. 2004. Polscope analysis of meiotic spindle changes in living metaphase II human oocytes during the freezing and thawing procedures. Human Reproduction 19(3): 6559.
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112. Vincent C, Johnson MH. 1992. Cooling, cryoprotectants, and the cytoskeleton of the mammalian oocyte. Oxford Review of Reproductive Biology 14: 73100.
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Appendix 2: Risk Assessment of the Use of Frozen Eggs
Risk is a combination of two concepts:
the likelihood of an effect occurring
the consequences of an effect if it occurs.
Likelihood and magnitude can be described qualitatively or quantitatively.
Likelihood
To consider the likelihood of risks associated with the use of frozen eggs, ACART has used the following categories.
DescriptorDescriptionAFrequentIs expected to occur again either immediately or within a short period of time (likely to occur most weeks or months)BLikelyWill probably occur in most circumstances (several times a year)CPossiblePossibly will recur might occur at some time (may happen every one to two years)DUnlikelyPossibly will recur could occur at some time in two to five yearsERareUnlikely to recur may occur only in exceptional circumstances (may happen every five to 30 years)
Consequences
To assess the consequences of the risks associated with the use of frozen eggs, ACART has used the following descriptors of consequences.
DescriptorDescriptions (risks and costs)SeriousPatients whose death is unrelated to the natural course of the illness and differs from the immediate expected outcome of the patients managementMajorPatients suffering a major permanent loss of function (sensory, motor, physiological or psychological) unrelated to the natural course of the illness and differing from the expected outcome of patient managementModeratePatients with permanent reduction in bodily function (sensory, motor, physiological or psychological) unrelated to the natural course of the illness and differing from the expected outcome of patient management or any of the following:
increased length of stay as a result of the incident
surgical intervention required as a result of the incidentMinorPatients requiring an increased level of care, including review and evaluation, additional investigations, or referral to another clinicianMinimumPatients with no injury or increased level of care or length of stay
Comparing the risks
ACART has used the following table to quantify and compare each aspect of the risk associated with the use of frozen eggs. Known risks associated with adjunct procedures (such as the collection of eggs for storage and IVF) are included in the table for additional information.
ConsequencesLikelihoodSeriousMajorModerateMinorMinimumA (frequent)EEHMMB (likely)EEHMLC (possible)EHHMLD (unlikely)EHML
Miscarriage rate:
using salt/low sucrose method: three of six pregnancies lost before 12 weeks
using initial low sucrose method: 20% miscarriage
using triple sucrose method: three losses from 18pregnancies
The latter two rates are not significantly different from those associated with embryo freezing, though the numbers are too low to make meaningful comparisons.LE (rare)HNo major malformations in children born following the use of frozen eggs have been reported, though studies do indicate a general increased risk of malformations in children born through IVF (using both fresh and frozen embryos). Because of the potential damage to egg chromosomes, the risk of congenital malformations should be monitored.MLLLegend:
E = extreme riskH = high riskM = moderate riskL = low risk
It should also be noted that a number of eggs do not survive the freeze/thaw process intact. Eggs in which the spindle has been damaged are unlikely to proceed through fertilisation. Similarly, damage to the cytoskeleton would prohibit normal fertilisation and development of the embryo. In both situations this abnormal material is discarded and not transferred to the patient, thereby having n o i m p a c t o n t h e o b s t e t r i c o u t c o m e .
R e l e v a n t p r i n c i p l e s o f t h e H u m a n A s s i s t e d R e p r o d u c t i v e T e c h n o l o g y A c t 2 0 0 4
A C A R T i s g u i d e d i n i t s d e c i s i o n - m a k i n g b y t h e p r i n c i p l e s o f t h e H A R T A c t 2 0 0 4 . A l l o f t h e s e p r i n c i p l e s a r e r e l e v a n t t o a r i s k "a c c e p t a b i l i t y analysis. The principles can be divided between health and ethics.
Health principles
The health and wellbeing of children born as a result of the performance of an assisted reproductive procedure or an established procedure should be an important consideration in all decisions about that procedure.
The human health, safety and dignity of present and future generations should be preserved and promoted.
Although all persons are affected by assisted reproductive procedures and established procedures, women, more than men, are directly and significantly affected by their application, and the health and wellbeing of women must be protected in the use of these procedures.
ACART considers that the use of frozen eggs is consistent with the above principles. In particular, ACART has considered the health and wellbeing of children born as a result of the use of frozen eggs and considers that, at this stage, the evidence does not indicate increased risks to those children above those associated with IVF alone. Although there is some evidence that transient chromosome changes to eggs can occur during the freezing/thawing processes, at this stage there is no evidence to suggest that these changes remain beyond embryo formation. Eggs that are permanently damaged during a freeze or thaw process are likely to be discarded.
Allowing the use of frozen eggs ensures that women who have frozen eggs to preserve their fertility have the opportunity to use those eggs, thereby protecting their health and wellbeing.
Ethical principles
No assisted reproductive procedure should be performed on an individual, and no human reproductive research should be conducted on an individual, unless the individual has made an informed choice and given informed consent.
Donor offspring should be made aware of their genetic origins and be able to access information about those origins.
T h e n e e d s , v a l u e s a n d b e l i e f s o f M o r i s h o u l d b e c o n s i d e r e d a n d t r e a t e d w i t h r e s p e c t .
T h e d i f f e r e n t e t h i c a l , s p i r i t u a l a n d c u l t u r a l p e r s p e c t i v e s i n s o c i e t y s h o u l d b e c o n s i d e r e d a n d t r e a t e d w i t h r e s p e c t .
G i v e n t h e r e l a t i v e n o v e l t y o f u s i n g f r o z e n e g g s , i t is important that individuals considering using frozen eggs are informed about all aspects of the eggs use.
ACART considers that frozen eggs should also be able to be donated. Under the HART Act 2004, the donor register will ensure that any child born from a donated egg will be made aware of his or her genetic origins.
Allowing for eggs to be both frozen and used takes account of the various ethical, spiritual and cultural perspectives that couples undergoing fertility treatment may hold, by allowing the freezing and use of eggs where embryo freezing may be unacceptable to them.
Effect of data uncertainty
This discussion document identifies the following issues with the current data.
There has been no genetic or developmental follow-up of babies born following egg freezing, and in other studies very little information is given regarding the pregnancies or births (apart from some reporting of the term of pregnancy, sex of offspring and birthweight).
A confounding factor in reporting the total number of births from frozen eggs is that, in many reports, the final outcome was only measured as foetal heart detection (and not actual live birth), and this data was generated using two different freezing techniques.
Many of the early studies related to small groups of patients.
The literature lacks comparison between fresh eggs and frozen eggs within the same clinic, in which all factors apart from the freezing are the same.
Where studies have attempted to compare fresh and frozen eggs, the studies are deficient in meaningful embryo quality assessment between fresh and frozen eggs.
Data collected by the National Perinatal Statistics Unit (Australia and New Zealand fertility outcomes) does not currently report analysis of data collected from the use of frozen eggs.7
ACART considers that the above uncertainties point to a need to ensure ongoing monitoring and research on births from frozen eggs.
Effect of cumulative risk
At this stage the only known risk directly associated with the use of frozen eggs is the miscarriage rate outlined above. As noted, there are some risks associated with the egg collection procedure, but this procedure is separated in time from the actual use of the frozen eggs, and the risks are therefore not really cumulative.
Revealed preferences
If the risks of this technology are similar to those of other, more common, assisted reproductive technologies, this might indicate that people would consider that the risks associated with the technology are acceptable.
Because of the availability of more effective technologies, egg freezing (and therefore use) is still relatively rare. In the literature at present there are reports of egg freezing in 15 countries (United States, Australia, Canada, Spain, Germany, Hungary, Czech Republic, Brazil, Argentina, Colombia, China, Taiwan, Korea, Japan and Italy). These reports indicate that over 1820 patients have frozen more than 11,693 eggs. In these studies, 160 babies have been reported from the freezing of 11,248 eggs, which equates to 1.4 babies for every 100 eggs frozen.
The numbers are comparatively low compared to IVF or other reproductive technologies. However, this is likely due to the availability (in most countries) of embryo freezing and the use where possible of fresh embryo transfer. However, the change to the law in Italy to prohibit embryo freezing could result in an exponential increase in the number of patients using egg freezing.
Although there are currently no overseas prohibitions on egg freezing, a recent article indicated that the Hungarian Ministry of Health is currently working on a proposal that may place a moratorium on egg freezing in Hungary. The concern is that the safety of the technology has not been proven and that there is a high risk to the genetic material within the egg, which translates to a significantly increased risk to the offspring.
There has not been a high uptake of egg freezing worldwide. However, a number of people (at least 1820) clearly consider the risks associated with the technology to be acceptable.
In New Zealand, a handful of women hold frozen eggs with fertility providers. It is difficult from such small numbers to assume that these women consider the risks associated with the use of those eggs to be acceptable or that there is a demand in New Zealand for the technology to become available.
Risk reduction/management
The risks associated with the use of frozen eggs can be mitigated or managed by using clinical indicators. Appendix 1 of this discussion document notes that the exclusion of potential patients would be based on clinical indicators (for example, those patients for whom the risk of ovarian hyperstimulation would adversely affect the prognosis. These clinical indicators are already used by clinics when offering egg freezing.
Carefully monitoring the pregnancies of women who conceive using previously frozen eggs may also reduce the risks to the unborn child and the mother. It will also be important for ACART to monitor any outcomes of births from the use of frozen eggs in New Zealand.
Benefits
Although section 6(d) of the HART Act 2004 only asks ACART to provide an assessment of the risks of the procedure, some consideration of the benefits of the procedure may help to assess the acceptability of those risks. If the benefits are significant, these benefits may make the risks associated with the technology more acceptable.
The benefits associated with the use of frozen eggs are no different from the benefits offered by other assisted reproductive technologies, such as IVF, or the use of fresh eggs. It is simply another potential path for a person to take in an attempt to conceive a child. For women who have frozen eggs before cancer treatment, the use of those eggs in treatment may be their only option for bearing children that are genetically related.
However, there are a number of additional benefits associated with the overall technology of freezing and subsequently using frozen eggs, including:
being able to freeze eggs where embryos cannot be formed due to absence of sperm for fertilisation
potentially preserving the fertility of a young single woman with a malignant condition that threatens her fertility
freezing donated eggs to better synchronise with the recipients cycle
for some people, eliminating the ethical and religious issues associated with creating and storing multiple embryos, including the dilemmas patients face when discarding embryos, or legal issues relating to the use of embryos following separation.
In general, ACART considers that the benefits associated with the use of frozen eggs are significant and outweigh the risks associated with the procedure.
Decision-maker
From the ethical analysis provided above, there appear to be very few issues associated with the use of frozen eggs. Indeed, allowing eggs to be frozen may eliminate some difficult ethical or religious issues for some people.
Egg freezing is a technology that is likely to be used in only a small number of cases. At this stage, freezing embryos is a far better option. However, for a small number of people, egg freezing is desirable for medical, ethical/religious or social reasons.
A technology that has very few attendant ethical issues does not require oversight by ECART. If the majority of risks are those that are better dealt with in discussion between clinician and patient, this might indicate that the risks are acceptable for the purpose of making that procedure an established procedure. In terms of the use of frozen eggs in fertility treatment, ACART considers that the risks and ethical issues are such that a reasonable individual (in that individuals position) could weigh up and decide on the risks themselves, in discussion with their clinical team. ACART proposes that the use of frozen eggs, therefore, should be an established procedure.
Appendix 3: Members of ACART
Sylvia Rumball(Chairperson)
Sylvia Rumball is Assistant to the Vice Chancellor (Ethics and Equity) at Massey University. She has a PhD in chemistry and for many years taught chemistry and undertook research in structural biology at Massey University.
She has extensive international, national and local experience on ethics committees through past membership with the UNESCO International Bioethics Committee, the Health Research Council Ethics Committee and the Massey University Human Ethics Committee; current membership of the Ethics Advisory Panel of the Environmental Risk Management Authority and the MASH Trust Ethics Committee; as past Chair of the National Ethics Committee on Assisted Human Reproduction; and as current Chair of the Massey University Human Ethics Chairs Committee.
Professor Rumball is also a member of the recently established International Council for Science Committee on Freedom and Responsibility in Science, a member of the Massey University Council and an auditor for the New Zealand Universities Academic Audit Unit.
In 2007 she was made a Companion of the New Zealand Order of Merit for services to science. She is also the recipient of a Palmerston North City Council Civic Award, a Distinguished Alumni Award from the University of Canterbury and a New Zealand Science and Technology medal.
Gareth Jones
Gareth Jones is Deputy Vice Chancellor (Academic and International) at the University of Otago, where he is also Professor of Anatomy and Structural Biology. He qualified in medicine and neuroscience (BSc Hons, MBBS) at University College London (UCL) and has DSc and MD degrees from the University of Western Australia and the University of Otago, in science and bioethics respectively. He was made a Companion of the New Zealand Order of Merit in 2004 for his contributions to science and education. He has published extensively in neuroscience, anatomy education and bioethics. His recent publications include: Speaking for the Dead: Cadavers in biology and medicine (2000), Stem Cell Research and Cloning (editor, 2004), Medical Ethics (co-author, 4th edition, 2005) and Designers of the Future (2005).
John Forman
John Forman is a parent of adult twins with a rare genetic disorder, alpha mannosidosis, and his family experience with physical and intellectual disability has drawn him into a range of health and disability sector networks over the past 30years. He has also spent many years in disability support service provision, mainly in community mental health. Since the late 1990s John has focused on the development of patient/family support networks in New Zealand and internationally, with an emphasis on partnership with health professionals, policy agencies and researchers to promote prevention, treatments and cures for rare disorders.
He has volunteer roles on the boards of several local and international advocacy groups. His paid role is Executive Director of the New Zealand Organisation for Rare Disorders, where he advocates for the increased application of genome knowledge and biotechnology to control health and disability problems, with a sharp eye on the ethical issues to ensure safety for the patients and their families.
Richard Fisher
Richard Fisher is a gynaecologist with a sub-specialty practice in reproductive medicine. He is a co-founder of Fertility Associates and has been an active advocate for infertile couples for 20 years. He is the only New Zealander to have been elected President of the Fertility Society of Australia. Richard is a member of a number of professional associations and is a member of the Institute of Directors in New Zealand Inc. He is married and has four children. Richard brings a medical professionals viewpoint to ACART, which is tempered by a recognition of the need for community involvement and decision-making in this area.
Christine Rogan
Christine Rogan has worked to actively promote health for 15 years. She is a past President and life member of the Auckland Infertility Society and became the first National Development Officer for the New Zealand Infertility Society (now called Fertility NZ). She currently works as a health promotion advisor with a non-government public health organisation. In addition, Christine is a non-medical Performance Assessment Committee Member for the Medical Council of New Zealand and the Dental Council of New Zealand. Christine has a tertiary qualification in social sciences from Massey University and lives on the North Shore of Auckland with her daughter.
Ken Daniels
Ken Daniels is Adjunct Professor in the School of Social Work and Human Services at the University of Canterbury. He was appointed to establish social work education and training at Canterbury in 1975 and retired in 2004. For over 30 years he has been actively involved in studying, writing, counselling and policy development in the psychosocial aspects of assisted reproductive technology (ART). His particular focus has been on the children and families that result from ART.
He served for nine years on NECAHR the last three as Deputy Chair. Professor Daniels has carried out research in a number of countries and has been used as a policy consultant in several overseas jurisdictions. He has published extensively, and his book Building a Family with the Assistance of Donor Insemination is used by parents and professionals throughout the world. Professor Daniels is also a board member of the Richmond Fellowship of New Zealand.
Mark Henaghan
Mark Henaghan is Professor and Dean of Law at the University of Otago and Principal Investigator of the Human Genome Project, Law and Ethics for the Future, which is sponsored by the Law Foundation New Zealand. Professor Henaghans primary research interests are family law and medico-legal law involving children.
Andrew Shelling
Associate Professor Andrew Shelling is head of the Medical Genetics Research Group, which is primarily interested in understanding the molecular changes that occur during the development of genetic disorders, focusing on infertility and reproductive cancers, but also including cardiac disorders and inflammatory bowel disease. He is currently an associate editor for the journal Human Reproduction which is one of the leading journals in the area of reproductive research.
Dr Shelling has a special interest in understanding the cause of premature menopause, and his research is internationally recognised for identifying genetic causes of this common cause of infertility. He initiated the development of a support group for women with premature menopause in New Zealand. Dr Shelling is currently Deputy Head of the Department of Obstetrics and Gynaecology, University of Auckland, and is extensively involved in teaching reproduction, genetics and cancer at the university. Dr Shelling has recently served as President of the New Zealand branch of the Human Genetics Society of Australasia. He has also recently been appointed as a trustee for the Nurture Foundation for Reproductive Research (Nurture).
Ian Hassall
Ian Hassall is a New Zealand paediatrician and childrens advocate. He was New Zealands first Commissioner for Children from 1989 to 1994. His career has entailed working for children and their families as clinician, strategist, researcher and advocate. He is at present Senior Lecturer in the Children and Families Programme of the Institute of Public Policy at Auckland University of Technology (AUT).
Dr Hassall teaches the Master of Arts (Children and Public Policy) at AUT. He is a member of the Steering Group and Project Team for Every Child Counts, a coalition of child advocacy and service organisations, whose aim is to place children centrally in government decision-making. He is married to Jenny, is father to four children and grandfather to five. He is the Childrens Commissioners nomin e e t o A C A R T .
C i l l a R u r u h i r a H e n r y
C i l l a R u r u h i r a ( Q S M J P ) g r e w u p u n d e r t h e m a n t l e o f t h e k +n g i t a n g a m o v e m e n t , d e e p l y e n t r e n c h e d i n W a i k a t o k a w a ( p r o t o c o l ) a n d t i k a n g a ( t e a c h i n g s ) . H e r h a p k c o n n e c t i o n s a r e N g t i W a i r e r e . H e r o t h e r t r i b a l c o n n e c t i o n s a r e H a u r a k i , N g t i H a k o . C i l l a h a s t h r e e c h i l d r e n a n d f i v e m o k o p u n a . F r o m t h e e a r l y y e a r s o f P l a y c e n t r e a s a y o u n g m o t h e r , C i l l a m o v e d o n t o j o i n t h e D e p a r t m e n t o f S o c i a l W e l f a r e a s a r e s i d e n t i a l s o c i a l w o r k e r w o r k i n g w i t h t e e n a g e d a d o l e s c e n t s . I n h e r c a p acity as a healer she has worked with potential teenage suicide victims and their parents in South Auckland. Over the years Cilla has shared her knowledge and expertise with various social services groups, both government and iwi based.
Cillas passion is children, and she is a Resource Panel Member for the care and protection of children and their families services through the government agency Child, Youth and Family (CYF). She is a M o r i s p e c i a l i s t c o n s u l t a n t , B i c u l t u r a l T h e r a p y M o d e l ( B T M ) , D e p a r t m e n t o f C o r r e c t i o n s P s y c h o l o g i c a l S e r v i c e s , H a m i l t o n , w o r k i n g w i t h M o r i i n m a t e s a t W a i k e r i a P r i s o n . C i l l a i s a l s o t h e M o r i W o m e n s W e l f a r e L e a g u e b r a n c h r e p r e s e n t a t i v e o n t h e N a t i o n a l C o u n c i l o f W o m e n o f N e w Z e a l a n d ( N C W N Z ) .
M a u i H u d s o n
M a u i H u d s o n l i v e s i n R o t o r u a , a n d h i s i w i a f f i l i a t i o n s a r e w i t h W h a k a t o h e a , N g R u a h i n e a n d T e M a h u r e h u r e . M a u i h a s p r o f e s s i o n a l q u a l i f i c a t i o n s f r o m A u c k l a n d U n i v e r s i t y o f T e c h n o l o g y ( A U T ) i n p h y s i o t h e r a p y , e t h i c s a n d M o r i h e a l t h , a n d c u r r e n t l y w o r k s f o r t h e I n s t i t u t e o f E n v i r o n m e n t a l S c i e n c e a n d R e s e a r c h L t d ( E S R ) i n a M o r i d e v e l o p m e n t p o s i t i o n . I n t h i s r o l e h e i s r e s p o n s i b l e f o r i n t e r n a l d e v e l o p m e n t , p r o v i d i n g c u l t u r a l a n d e t h i c a l a d v i c e t o r e s e a r c h e r s , a n d e s t a b l i s h i n g r e s e a r c h r e l a t i o n s h i p s w i t h M o r i a n d P a c i f i c c o m m u n i t i e s . M a u i i s a J P a n d h a s p r e v i o u s l y b e e n a m e m b e r o f t h e E t h i c s C o m m i t t e e o n A s s i s t e d R e p r o d u c t i v e T e c h n o l o g y ( E C A R T ) a n d t h e A u c k l a n d R e g i o n a l H e a l t h a n d D i s a b i l i t y E t h i c s C o m m i t tee. He is married and has three children.
Robyn Scott
Robyns background is in both not-for-profit management and education. She studied at Wellington College of Education (now the Faculty of Education, Victoria University of Wellington) and Victoria University of Wellington before embarking on a career in primary school teaching and the teaching of speech and drama and music. From there she moved to managing a not-for-profit organisation, working particularly in the area of health support and health advocacy.
Robyn is currently Executive Director of Philanthropy New Zealand and is charged with leading and developing the key organisation that works to motivate and inspire philanthropists and grant makers.
Robyn lives in Wellington with her husband and two school-aged children. Outside work she enjoys a range of mostly family activities that tend to centre around childrens sport and cultural events, and also enjoys travel and reading. She is an alumna of Leadership New Zealand, having graduated in 2006.
Submission Form
Please provide your contact details below.
Name:If this submission is made on behalf of an organisation, please name that organisation here:Please provide a brief description of the organisation if applicable:Address/email:Interest in this topic (for example, user of fertility services, health professional, member of the public):
Please note that all correspondence may be requested by any member of the public under the Official Information Act 1982 (the Act). If there is any part of your correspondence that you consider should be properly withheld under the legislation of the Act, please make this clear in your submission, noting the reasons why you would like the information to be withheld.
If information from your submission is requested under the Act, the Ministry of Health (the Ministry) will release your submission to the person who requested it. However, if you are an individual, rather than an organisation, the Ministry will remove your personal details from the submission if you check the following box.
( I do not give permission for my personal details to be released to persons under the Official Information Act 1982.
All submissions will be acknowledged by ACART, and a summary of submissions will be sent to those who request a copy. The summary will include the names of all those who made a submission. In the case of individuals who withhold permission to release personal details, the name of the organisation will be given if supplied.
Do you wish to receive a copy of the summary of submissions.
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Questions
Question 1:
Given these risks and benefits, what is your opinion on ACARTs proposed advice to the Minister of Health? Please give reasons for your views.
(See chapter 3 for a discussion of risks and benefits, and chapter 6 for the proposed advice.)
Question 2:
What is your view on the information that ACART suggests should be collected to monitor the use of frozen eggs in fertility treatment?
(See chapter 3.)
Question 3:
Has ACART identified all the ethical issues relevant to the use of frozen eggs in fertility treatment? Do any of these issues affect ACARTs proposed advice that the use of frozen eggs should be allowed in fertility treatment? If so, how?
(See chapter 5 for a discussion of the ethical issues, and chapter 6 for the proposed advice.)
Question 4:
Should the use of frozen eggs in fertility treatment become an established procedure? If not, why, and how should the use of frozen eggs be regulated?
Question 5:
Should the use of frozen eggs in fertility treatment be limited to the individuals the eggs came from, or should frozen eggs be able to be donated to others for use in fertility treatment?
Question 6:
Should frozen eggs be able to be donated for research purposes?
Question 7:
Do you have any further comments to share with ACART?
Ovarian tissue freezing is a new technology that has been developed for preserving reproductive potential in young women with malignant disease who are often rendered menopausal following C G J
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