Embryo freezing is a well-established form of assisted
conception treatment. An increasing number of IVF clinics worldwide
are now able to freeze spare embryos for later transfer. The first frozen
embryo baby was born in 1984. Embryo cryopreservation allows multiple
embryo transfers from a single egg collection and improves the chances
of livebirth.
- Allow maximizing the potential for conception for IVF and prevent
wastage of viable normal spare embryos. Perhaps this is the most important
advantage of cryopreservation. Approximately 50% of women may have
spare embryos available for freezing. In some clinics, the pregnancy
and live birth rates with frozen-thawed embryo transfer is as high
as those achieved with fresh embryo transfer.
- Freezing all embryos for subsequent transfer may be advised for women
who are at a high risk of developing severe ovarian
hyperstimulation syndrome following ovarian stimulation for in-vitro
fertilization (IVF).
- When embryo implantation may be compromised in cases such as the
presence of endometrial polyps, poor endometrial development, break
through bleeding near the time of embryo transfer or illness.
- Difficulty encountered at fresh embryo transfer e.g. cervical stenosis
(inability to pass through the cervical canal because the cervix is
narrowed or scarred, etc).
- Cryopreservation of embryos is very important to be incorporated
in the egg donation programs. It is not always possible to synchronize
the recipient’s cycle with that of the egg donor. In some countries,
it is mandatory to freeze all embryos created from donated eggs, quarantined
for a period of six months and until the donor have a repeat negative
screening tests.
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As a result of successful cryopreservation programs,
frozen embryos have also become available for donation to infertile
couples.
- Before cancer chemotherapy or radiotherapy.
