Oocyte cryopreservation holds significant potential as an option for preserving female fertility, especially in patients undergoing aggressive radiation or chemotherapy. Following an intensive review, the British Fertility Society (BFS) and the Association of Clinical Embryologists (ACE) have issued new clinical guidelines on egg freezing technologies for UK clinics.

Some of the key recommendations are as follows:
• Though egg freezing is an emerging technology in the field of fertility treatment, various factors, including the success rates and the number of eggs obtained, influence the effectiveness of the techniques. Hence, further large-scale, appropriately controlled trials are warranted to enhance the knowledge base on the most effective techniques

• Women opting for egg freezing should be given appropriate counseling, and informed on the safety and probable success rates that can be obtained. Proper guidance should be offered regarding the benefits and disadvantages of the procedure in contrast to other treatment options. A greater success rate could be associated with cryopreservation of the embryo rather than the oocyte, under favorable circumstances

• While comparing slow cooling with vitrification, initial studies have shown higher success rates with the former. However, the recommendations have necessitated further studies to substantiate the optimum chemical composition needed for egg freezing, as well as the long-term efficacy and safety of vitrification

• For obtaining optimum treatment results, it is recommended to collect mature ova after ovarian stimulation, similar to IVF treatment protocols. Also, the type of ovarian stimulation used should be customized, based on the individual patient’s needs. For example, in the case of patients suffering from hormone sensitive cancers, treatment with minimum exposure to estrogen is preferred

• Studies indicate increased chances of success on using ICSI for the fertilization of thawed eggs when compared to conventional IVF procedures. During ICSI, sperms are incubated along with the egg in the ratio of 1:1 as opposed to approximately 75,000:1 in IVF

• In clinical situations when freezing of immature eggs is essential, they can be harvested without performing ovarian stimulation. However, more research is required to identify optimum strategies for immature egg freezing and in vitro maturation upon thawing

Both BFS and ACE substantiate the use of this technology for preserving fertility in women likely to face future infertility due to surgery, radiation or chemotherapy. However, the use of cryopreservation to thwart age-related fertility decline has been dissuaded by both the authorities.

As per the statistics of the Human Fertilisation and Embryology Authority (HFEA), in UK, 78 patients opted for cryopreservation for non-medical reasons in 2007, more than twice the number in 2006 (around 33). Earlier this year, the Royal College of Obstetricians and Gynecologists (RCOG) of UK and BFS issued a joint statement, in which serious concerns against the use of the egg-freezing technology for non-medical reasons, such as career priorities and other lifestyle reasons, were raised. In 2007, the American Society for Reproductive Medicine (ASRM) expert committee cautioned against social egg freezing; arguing that the availability of the technology would convey a false impression that freezing of egg ensures conception later in the life.

With several studies suggesting certain disadvantages of oocyte cryopreservation, such as reduced success rate of pregnancy and increased chances of conceiving less-healthy babies, legislation for regulating and monitoring the technology attains paramount importance.

References

1. New clinical guidelines for egg freezing in the UK. Press Release. British Fertility Society. Last accessed November10, 2009.