Egg Banks – An Update!
Egg donation developed as an extension of in-vitro fertilization technology and has been utilized since 1984. Some of the reasons that women might require donor eggs include the following:
1) Diminished ovarian reserve – In this situation, the quality of a woman’s eggs has suffered most commonly because of advancing age, but potentially as the result of prior pelvic surgery, pelvic radiation, cancer therapy, or genetic abnormalities.
2) Premature ovarian failure – This is a more extreme condition sometimes caused by genetic abnormalities that lead to either total absence of eggs from birth, or depletion of the pool of available eggs very early in life.
3) Genetic disease carrier – A relative small number of women are found to be carriers of serious genetic diseases for which no testing is available to diagnose the disease using available embryonic testing (preimplantation genetic diagnosis.
4) Same sex male couples – Donor eggs and a gestational carrier are required in order to achieve a successful pregnancy.
5) Recurrent pregnancy loss – in certain circumstances repeated miscarriage may be caused by an unidentified egg problem.
For many years, donor egg treatment has involved donor identification and screening , synchronization of the donor and recipient hormonally, stimulation of the donor through controlled ovarian hyperstimulation, extraction of eggs from the donor, fertilization of eggs using sperm from the recipient couple, incubation of embryos for for 3-5 days in the IVF laboratory, followed by placement of embryos in the recipient’s uterus. This approach requires careful monitoring and treatment of both donor and recipient and has yielded excellent results. The number of patients utilizing egg donor treatment has been steadily increasing since 1984. As we have learned more about successful IVF treatment in general, egg donation success rates have also steadily improved. Broader understanding of the effects of egg aging have led to refinement in our ability to identify suitable egg donors. A donor’s age, ovarian reserve testing, and response to fertility medications are all factors in selecting suitable donors and maximizing success rates. We have also learned to screen recipients carefully for such things as uterine polyps, fibroids, or fluid filled fallopian tubes, all of which may be corrected prior to the actual donor egg treatment cycle. If a woman has been an egg donor more than once, her prior donation results in terms of eggs retrieved, number fertilized, and achievement of pregnancy may be available for review. In 2013, donor egg live birth rates from fresh donor egg embryo transfer are consistently reported in the 60-75% range. Most reproductive specialists agree that properly performed egg donation treatment represents one of the most successful and satisfying treatment options that may be offered to patients.
Recent advances in cryopreservation technology have led to our ability to successfully freeze eggs with excellent post thaw survival. While we have long been able to freeze human embryos successfully (since 1983), identifying egg freezing technology that enables the majority of eggs to survive freezing and remain capable of normal fertilization and embryonic development proved more difficult. The technology that has led to successful egg freezing is called “vitification” and involves very rapid freezing which is much less likely to damage the delicate genetic spindle fibers within the egg. As a result of this technology, egg banks have evolved, operating similarly to sperm banks. These banks offer frozen anonymous donor eggs that can be shipped to any properly equipped infertility clinic. Obvious advantages of frozen banked eggs are that they are readily available and there is no need to synchronize donor and recipient cycles. One disadvantage of frozen donor eggs are that the recipient usually does not receive as many eggs as she would in a fresh donor egg cycle in which she would usually have access to all of the eggs the donor produced in a given cycle. Typically, egg banks will provide 5-8 eggs to the recipient for a certain fee, whereas in a typical fresh egg donation cycle the recipient might have 10-15 eggs available. The larger number of eggs available in the fresh cycle leads to a greater opportunity for extra embryos that may be frozen and used later in a future cycle should the first treatment cycle fail. Because some eggs will not thaw successfully and some will not fertilize normally, the likelihood of obtaining frozen embryos from the frozen donor egg cycle is significantly lower than in a fresh egg donor cycle. Therefore, when considering cumulative pregnancy rates, fresh egg donation cycles will likely lead to higher overall live birth rates compared to a single frozen egg donor cycle.
The expense of a frozen donor egg cycle is likely to be lower than a fresh egg donor cycle. Preliminary studies suggest that the potential for a live birth using frozen donor eggs is equivalent to success rates using fresh donor eggs. Simply stated, preliminary studies suggest that 8 frozen donor eggs or 8 fresh donor eggs should result in similar live birth rates.
We have had approximately 30 years to investigate obstetrical and neonatal outcomes with frozen human embryos, while our experience with frozen eggs is much more limited. Banked frozen donor eggs are a reality. As with assimilation of in-vitro fertilization procedures in the early 1980’s, as well as the later applications of egg donation, embryo cryopreservation, and intra-cytoplasmic sperm injection, we must monitor and study frozen egg pregnancies as well as the children born through this technology carefully. It is important that patients be made aware that we are in the early stages of utilizing frozen eggs for procreation, and that although preliminary studies are very encouraging, long term studies in humans do not exist at this time.