Improvements in egg freezing techniques and donor egg banking

The current review examined the viability of cryopreserved egg donation for use with in vitro fertilization.

Egg (oocyte) donation is a process by which a woman provides eggs for purposes of assisted reproduction. It is one of the last resorts in IVF treatment for women who cannot use their own eggs due to poor egg quality, early menopause, or genetic disorders which could be passed on to their offsprings. However, the use of fresh donor eggs requires careful timing, as the donation of eggs must be carefully synchronized with the readiness of the recipient’s uterus for implantation. Unlike sperm donations, which are kept frozen in sperm “banks,” egg donations are generally fresh, and all of the eggs from one donor are given to one recipient. An egg banking system, in which the eggs are frozen for future use, may ease the process by making eggs available when the recipient is ready to receive them. The current review explores the use and viability of cryopreservation, or freezing, of donor eggs. 

Cryopreservation of eggs can be a difficult procedure, as ice crystals that form during freezing can damage the cell, decreasing the odds of fertilization and successful pregnancy. Vitrification is a new process, involving very fast freezing times, that decreases the possibility of ice crystal formation. One study examining the use of eggs frozen through vitrification reported pregnancy rates of 21.4%, while a second study reported 63% of patients having successful pregnancies. A third study reported an 85% pregnancy rate using frozen eggs, which was comparable to the rates seen with fresh egg donations. Therefore, the vitrification technique allows for successful egg freezing and thawing enabling egg banking.

The timing of fresh versus frozen egg donations has also been shown to have an important impact on the success of the procedure. Studies have shown that the time spent waiting for donor eggs to become available increases the odds of women having to cancel the treatment, for reasons such as endometrial bleeding. As the use of frozen eggs does not involve any wait time, a women many begin treatment as soon as her uterus is ready for implantation, which leads to few, if any, cancellations.

Vast improvements in egg freezing have occured in recent years, which make possible the banking of eggs.

This review concluded that vitrification, a new process for egg cryopreservation is a safe and effective alternative to fresh egg donation in infertile women.

Cryopreserved donor eggs are now available and are increasingly used for assisted reproduction.