The process of oocyte retrieval is the same as that is used in IVF | Photo credit: Pexels
By Dr S.M Rahman and Dr Honey Qureshi
Kolkata: A woman’s reproductive life span is finite and depends on the numbers of oocytes with which she is born. Human oocyte cryopreservation (egg freezing) is a technique that has been used to enable women to postpone pregnancy whether for medical reasons and social reasons like for career goals or studies. The newer technology of freezing (vitrification) made egg freezing a feasible option for fertility preservation in women.
The process of oocyte retrieval is the same as that is used in IVF. Here, hormones injections are given for 10 to 12 days to stimulate the ovaries and when eggs are matured, they are removed by transvaginal route with USG guidance under sedation. These eggs are frozen and stored to be used as fertilized embryos for future pregnancy.
Women who are undergoing chemotherapy or radiotherapy for cancer treatment can choose egg freezing before starting it. Likewise, genetic conditions such as fragile x permutations and mosaicism for monosomy x predispose women to premature ovarian failure and oocytes cryopreservation is an option for them. Oocytes freezing can be an important fertility option in women with endometriosis who may experience reduced reserve post-surgery, women with an autoimmune disease requiring gonadotoxic treatment. Another application is emergency oocytes cryopreservation where sperm extraction from male partners with non-obstructive azoospermia had failed.
There are not yet sufficient data to recommend egg freezing merely as the purpose of circumventing reproductive ageing in healthy women. It is recommended that women should be thoroughly counselled about the current lack of data on efficiency as well as risk cost and alternative to elective oocyte cryopreservation or social egg freezing. According to the ESHRE task force on ethics and law (2012) egg freezing for age-related fertility decline is considered acceptable and social egg freezing has become popular and demand for the procedure has increased rapidly.
Other applications of oocyte freezing include donations programmes and storage of spare gametes during IVF. Research into oocytes cryopreservation was accelerated by legislative restrictions on the storage and disposal of embryos.
Embryos freezing could not be an option for all couples because of personal religions or moral objections and the fate of stored embryos lead to major disagreements in case of divorce and separation.
Successful pregnancy was first achieved in late 1980 using slow freezing and rapid thaw technique. The introduction of vitrification as a freezing technique led to a superior success rate more studies suggested that IVF using vitrified/warmed oocytes could produce similar fertilization and pregnancy rate to IVF with fresh oocytes. The first live birth following vitrification was achieved in 1999. This promoted oocytes freezing into a growing no of IVF clinics. In terms of outcomes mean birth weight and incidence of the congenital anomaly are similar in an infant born following frozen oocytes to those born from spontaneous conception or through regular IVF.
Oocyte cryopreservation into donation programmes simplifies the logistics of ART cycles, allow recipients to review the list of donors and minimize waiting times.
Although oocytes freezing is a breakthrough for reproductive autonomy and emancipation for women there are risks involved with the procedure. Ovarian hyperstimulation and risk during oocytes retrievals like bleeding and infections are always there. The disadvantage of cryopreservation of mature oocytes in cancer patients is delaying the cancer treatment or may carry a particular risk for those patients with a hormone receptive cancer. When Older women use their cryopreserved egg, they are more likely to experience pregnancy complications like preeclampsia, hypertension, and gestational diabetes etc. although social egg freezing gave women to make their reproductive choice it should not be considered as insurance against future infertility.
Oocyte cryopreservation is now an established technology with a wide range of indications. It is important to continue auditing outcomes and reporting long term to follow up of children born from frozen and thawed oocytes.
(Dr S.M Rahman is Medical Director, Cradle Fertility Centre and Dr Honey Qureshi is a Consultant Gynecologist and Infertility expert, Cradle Fertility Centre, Kolkata)
(The opinions expressed are personal and do not necessarily endorse the views of Times Now)