Egg or oocyte freezing has been around for years, but up to a few years ago was only available as an experimental technique of fertility preservation, and with limited success. While embryo cryopreservation (freezing) has been successful for the last two decades, freezing unfertilized eggs or oocytes is trickier. Eggs are more susceptible to damage from ice crystallization than embryos during the freezing process. Up to a few years ago, a young and/or single cancer patient who wanted to preserve her future fertility, only had the option of fertilizing her own eggs with donor sperm. Also, some couples were faced with the moral and/or religious beliefs in having to decide what to do with multiple unused embryos. A third concern, were from young women, either single or married, that wanted to delay childbearing but were concerned about “getting too old and/or having problems” with resulting increased difficulty with achieving pregnancy; or at being at increased risks of chromosome abnormalities and miscarriages if they delayed childbearing for too long.
With these newer techniques of rapid egg freezing, or vitrification, it is now possible to cryopreserve the female egg (oocyte), as successfully as it has been to cryopreserve sperm. Egg freezing is still a new and mostly experimentally technology that has been shown to be highly effective in preliminary research. There are now a number of babies born with the use of egg vitrification technology; and ACFS now offers egg freezing for patients needing or choosing to preserve their future childbearing potential. We have had good results with vitrification of eggs. To date, there have been no increase in birth defects related to this process. Survival rates for eggs (oocytes) can reach as high as 85% and pregnancy rates as high as 65%, depending on the woman’s age. Pregnancy rates with egg vitrification, with subsequent thawing and fertilization, should be similar to success rates with that of frozen-thawed embryos. Once thawed, the egg can be fertilized using ICSI, an assisted reproductive technology, that injects one sperm directly into an egg.
