Fertility preservation for sperm has been around for some time and for embryos for over 10 years. Through recent advances, egg (oocyte) freezing is now available for women facing a number of life circumstances. Though still considered experimental, egg freezing has been performed successfully for some time and Dr. Marlane Angle, has been a leader in this endeavor. Egg freezing can be done for women who are undergoing cancer treatments that may have an adverse effect on the ovaries, women who know they want a baby in the future but are single now and wish to preserve their eggs while they have a lower likelihood of genetic abnormalities, couples who are uncomfortable with the idea of freezing embryos and emergency situations during the course of an IVF cycle in which the male partner is unable to produce a semen specimen.
Egg freezing is a modification of techniques that have been used for over 20 years for embryo cryopreservation. There are two methods currently in use for freezing eggs -slow cooling and vitrification. During slow cooling, the eggs are exposed to solutions to help them survive the freezing process, are loaded into small cryostraws then placed in a computer-driven freezing machine that drops the temperature down to -190oC (the temperature at which the straws containing the eggs will be stored). During the vitrification process, eggs are also exposed to solutions that will help them survive the cooling and warming process, are loaded into very small straws called CryoTips and are then plunged directly into liquid nitrogen for ultra-rapid cooling. Once vitrified, the CryoTips are stored at -190oC.
The differences between the two procedures lie primarily with the solutions that are used, the type of holding device used to store the eggs and the use of a computer to control the rate of cooling. The total number of babies born world-wide using eggs frozen with either method is estimated to be approximately 500, with the majority of them occurring in Italy, Japan and Brazil. Therefore, the American Society of Reproductive Medicine (ASRM) still views this procedure as experimental. At the current time, there is no way to guarantee to any patient that this procedure will be successful, regardless of which method is used.
Currently, there is no consensus among IVF professionals about which method is the best and there are advantages and disadvantages to both procedures. At the present time, however, the scientific evidence appears to be favoring vitrification as the superior method. Laurel Fertility Care’s Laboratory Director, Marlane Angle, PhD., uses vitrification techniques to cryopreserve all of the embryos that are frozen at Laurel Fertility Care and has traveled extensively around the world teaching other embryologists how to perform vitrification.
In order to freeze eggs, the patient must go through an IVF cycle to stimulate the ovaries and to retrieve the eggs. After retrieval, the eggs are immediately vitrified and may be stored for several years. There is not yet any data on exactly how long eggs may be cryopreserved and still survive the warming process, but estimates are that the time limit may almost be indefinite.
If you are interested in learning more about oocyte vitrification, please contact us to arrange an appointment.