Oocyte vitrification, is when a woman’s eggs are frozen for later use in fertility treatments. The frozen specimen is often an immature egg known as an oocyte.
The process of vitrification involves processing the oocyte with an increasingly stronger solution of cryoprotectants freezing (or antifreeze) to dehydrate and prepare it for freezing. The oocytes are then flash frozen. Afterwards, they are kept in liquid nitrogen at -196 °C or -321 °F. Recent studies show that the more mature the egg or oocyte is, the more successful the process will be. Freezing the egg can cause a hardened shell, which is why it must be injected by sperm instead of just placed in the uterus. The mitotic spindles, structures crucial to cell division, can become disrupted. After the oocyte is thawed, it is injected with sperm to fertilize the egg. Once fertilized, the egg will be placed into the woman, similar to IVF, or in vitro fertilization. The rate of pregnancy with oocyte vitrification is different for each woman, depending on how mature the egg is and how long it was frozen.
There seems to be no greater risk in abnormalities in children when using the oocyte vitrification procedure compared to other forms of assistive reproductive technology. Risks of abnormality are the same as if the egg was not frozen. However, the freezing and thawing does not eliminate the risks of congenital defects or fetal Egg Freezing abnormalities. Generally, the oocyte vitrificaiton process has been used for women going into a treatment that may cause them to become infertile, but recently more and more women have been freezing their eggs in order preserve the healthiest eggs possible.
Lately, fertility drugs have been used to help women superovulate, or produce multiple eggs. The extra eggs are taken and frozen in the oocyte vitrification process. The risk of crystallization has been reduced in the recent years, preventing chromosomal damage. The flash freezing is much better than the previous slow freezing methods. Some women may be looking into oocyte vitrification to prevent age-related problems. However, it is controversial whether this is beneficial or not. Only a few hundred pregnancies have resulted from oocyte vitrification, and it’s always within a short period of time – from hours to months, but never years. This a relatively new process and the American Society of Reproductive Medicine stands against the idea of freezing for future use.
Another technique of assistive reproductive technology is embryo freezing. This is when a fertilized egg is taken and frozen in the same process as the oocyte freezing method. It carres beter outcomes but it is available for only those who are married or have a partner. Using donor eggs is also an alternative to oocyte vitrification. This is when a different woman donates their egg, fertilized or not, to the infertile woman so that she may become pregnant.