Egg vitrification and storage

May be of benefit to any woman who is facing either the total loss or a decline in ovarian function, which may have a direct impact on her future fertility potential.

Examples of some scenarios are as follows:

1. For non-medical or social reasons, women may now wish to freeze their eggs to delay having their children until a more appropriate time in their lives – the so-called ‘safety-net’ option. The reason for this is that the efficiency of getting pregnant declines with age. In addition, the risks of miscarriage and of certain abnormalities (such as Down’s syndrome) increase with age.

Some women, who may not want to conceive until their later 30’s might want to consider using their eggs from their own ‘egg bank’, which they preserved when they were much younger. With an efficient egg freezing programme, the chance of conception in a single cycle with a 30 year-old woman’s eggs is up to 50%, compared with 15% when a woman is 40 years of age. The age of the woman when the eggs (as fertilised embryos) are replaced is almost irrelevant, it is the age of the woman when the egg was removed and preserved that counts most.

 2. Women suffering from endometriosis, a progressive disease that can impair ovarian function. The disease is becoming far more common in the western world, particularly among younger women.

 3. Cancer: the common treatments for cancer – chemotherapy and radiotherapy – have the common side effect of damaging the ovaries which may affect a woman’s future fertility. Unfortunately, for many cancer sufferers the need to get on quickly with cancer treatment does not allow sufficient time for us to set up a treatment cycle, stimulate the ovaries and collect eggs as this could delay cancer treatment for 2-6 weeks.

There may also be extra risks (for example in women with breast cancer) whose cancer may be sensitive to the high hormone (oestrogen) levels produced when stimulating drugs are given. We therefore take advice from a woman’s cancer specialist and would only advise proceeding with an attempt at egg freezing in selected cases where the timing of cancer treatment is less critical and hormone issues are not relevant.

 4. Women may freeze their eggs for other medical reasons.

 5. Eggs may also be frozen if more eggs than sperm are available in an ICSI treatment cycle. Alternatively, if the couple are having IVF but have ethical concerns about the creation of surplus embryos (eg. do not want more than two eggs inseminated when larger numbers of eggs are available), surplus eggs may be frozen.

Hundreds of babies have now been born from treatment using previously frozen thawed mature eggs from various centres around the world. However, this is still considered to be new technology and it is currently too early to give accurate figures about success rates. AVA is one of the European clinics what provides this service and has its laboratory operating procedures for a new method for egg freezing called vitrification.

 Based on Latvian legislation this procedure can be done to single women, heterosexual pairs or married couples.To have an IVF treatment cycle, create embryos using the partner’s or donor's sperm and then freeze the resulting embryos. Separate information about embryo freezing is available from AVA personnal Dr. Violeta Fodina violeta.fodina@avaclinic.lv   or clinic's coordinator Nadia Runce nadia.runce@avaclinic.lv

Background information on the Freezing of Human Eggs:

The freezing of human embryos is now a well established technique in most fertility centres around the world and provides a valuable extension to a standard IVF cycle where surplus embryos are available. Egg freezing, however, has proved much more difficult. Eggs are very large cells and their outer layers are quite water-resistant. The genetic information in mature eggs is also in a potentially more “fragile” state than in the human embryo.

Concerns about possible gene or birth defects have therefore led to a very cautious approach using frozen human eggs. Over the last few years research studies have culminated in the birth of hundreds of healthy infants from the use of frozen/thawed human eggs. These births have provided the impetus to develop and optimise the techniques needed to freeze, thaw and fertilise human eggs for use in reproductive medicine. In the earlier human studies, eggs that were frozen and thawed were shown to survive, but fertilisation rates were very low, apparently due to problems with the sperm being able to penetrate the outer shell of the egg (the zona pellucida).

More recently, the micromanipulation technique, ICSI (intracytoplasmic sperm injection), a technique routinely used in the management of male infertility, has been shown to overcome the problems of low fertilisation rates with frozen/thawed eggs. Internationally, this is now the recommended treatment technique used with egg freezing.

A more recent development in the procedure for storing human eggs – called vitrification – has led to the exciting prospect of being able to freeze eggs more efficiently and more safely. In 1992 CARE scientists produced Britain's first baby from vitrified human embryos. It has taken the intervening years to develop this technology for eggs.

With conventional methods of freezing more than half the eggs do not survive the freeze-thaw process. One reason is that when freezing a cell the water content forms ice crystals that can damage the cell.  As the egg cell is the largest cell in the body it is the most difficult to freeze for this reason. With vitrification more than 85% of eggs survive the freeze thaw process and a high percentage of these are capable of undergoing fertilisation.

The vitrification technique uses a rapid two stage process. The first dehydrates the egg to remove much of the liquid; the second stage freezes the eggs so rapidly that the transformation from liquid to solid is instantaneous. No ice crystals form and the consistency resembles a viscous glassy state (hence the term ‘vitrified’).

The Legal Position: Consent to Storage:

Before a clinic can store eggs, the woman is required to complete Consent Forms for storage. The forms are important and confirm the circumstances in which the woman will allow for the storage and usage of her stored eggs. Based on Latvian law all genetic material (including eggs and sperm) can be stored for 10 years. Shorter durations are at your own discretion.

Screening Tests:

Prior to eggs being stored clinics are now required to screen women for infection – HIV (Aids), Hepatitis B and Hepatitis C, syphilis. It is clinics policy to insist on screening results being available from no later than 6 months before eggs are received. Please note that blood donors are routinely screened. Clinic will therefore need evidence of blood donation (a letter confirming a recent donation), results of tests or we can arrange testing before the eggs can be received. At the present time is unable to offer egg storage to women who are HIV, Hepatitis B or C positive.

The Risks of the Technique:

The freezing of mature human eggs is still a new science, and much more work is still needed on ways of optimising the freezing, and thawing processes. It is therefore important to realise that there are no guarantees that any of the eggs will result in healthy eggs suitable for treatment.

Furthermore, until many thousands of babies have been born and followed up for several years, it will be very difficult to accurately quantify the risks of these techniques. It is also important to be aware that, like every assisted conception procedure, miscarriages, ectopic pregnancies and congenital abnormalities can occur. Whether these risks will be altered by freezing and vitrification will not be known for several years. As thawed eggs are inseminate during the ICSI technique, we have separate patient information documents on ICSI that you should read.

Counselling:

Because of the complexity of the issues underlying the need to contemplate egg freezing, we strongly recommend that patients undergo counselling with members of our staff  Dr. Violeta Fodina violeta.fodina@avaclinic.lv or clinic's coordinator Nadia Runce nadia.runce@avaclinic.lv

Egg Freezing – Is it suitable for you?

Patients considering the freezing of mature eggs will in the first instance have a consultation with one of our consultants.The patient will be assessed for the suitability of the technique in their personal circumstances, the technique will be described in detail and other possible options discussed.

If appropriate, arrangements will then be made for patients to come through for an egg freezing cycle and this can often be commenced 2-4 weeks after the initial consultation. But in case you would like to get more specific information you can contact our embriologist Indra Dundure indra.dundure@avaclinic.lv  

What about the impact of age?

Age has a major bearing on IVF success and therefore on the success of egg freezing. This is especially relevant for women in their later 30’s or early 40’s which is the time that we tend to see a decline in both the number of eggs collected and egg quality/viability.

Various tests are available (scans and blood tests) which will enable us to assess whether good numbers of eggs are likely to be available to collected. We would rarely recommend egg freezing for women over 41 at the current time and do not advise egg freezing if test results suggest low numbers of eggs are likely to be produced.

Egg Freezing – The Process:

This is very similar to the stimulated cycle common to IVF treatment. Medication is provided to

stimulate the ovaries and the eggs are collected under ultrasound guidance. This is exactly the same process used to collect eggs in an IVF cycle.

Later on the day of egg collection the oocytes will be frozen. Appropriate consent forms will be completed by the patient prior to egg collection and freezing.

The Consent Form is an important legal document, which includes not only the consent to the basic surgical aspects of the procedure, but also establishes the patient’s wishes in relation to a number of scenarios (e.g. what the patient would want done with the stored oocytes).

Treatment with Frozen Oocytes – An Outline:

This is very similar to the way in which treatment is carried out with frozen embryos. Hormone replacement tablets and pessaries are used to prepare the lining of the womb to receive the embryos.

The frozen oocytes are thawed, treated with the ICSI technique and, if fertilisation and development proceeds normally, replaced two or three days later in the uterus.

What to do Next?

If you do wish to freeze some eggs at AVA Clinics please contact us to arrange a consultation to discuss the process in more detail.