Embryo Freezing


Why is cryopreservation (freezing) of embryos important?

At Austin IVF, there is always the hope that there will be an excess number of embryos to freeze following an embryo transfer. However, depending on embryo development, that may or may not be the case.

Embryo freezing, sometimes called “cryopreservation” or “vitrification” allows patients fortunate enough to have an excess number of embryos that have reached a certain stage in development to have another chance for pregnancy. These patients would not need to have another ovarian stimulation and oocyte retrieval, and would not need to purchase more expensive stimulation medications and take shots.

Among the embryos that continue to divide and develop, there are some that meet specific criteria that allow them to be successfully frozen. These embryos are usually frozen (vitrified) at the Blastocyst stage on day 5, day 6 or day 7 after the eggs have been retrieved. Vitrification of these excess embryos provides an opportunity for achieving pregnancy at another time in the future, thus increasing the number of potential transfers from a single retrieval.

Austin IVF has seen promising results with the institution of our vitrification protocol that started in 2010.

Following this procedure, all frozen embryos are stored in liquid nitrogen, which has a temperature of -196 degrees C (-320 degrees F). Storage at this extremely cold temperature halts all metabolism of the embryo, allowing embryos to be safely stored for an indefinite period of time. We have noted remarkable changes in both survival rates and in pregnancy rates with vitrification. This allows Austin IVF and the Texas Fertility Center to give our patients the time they may need in order to start or to expand their family.

Austin IVF remains on the forefront of perfecting the protocols involved in embryo vitrification and the results that we are seeing in our laboratory are rapidly changing our approach to the IVF patients in Central Texas. Most importantly, delivery rates are now approaching those rates seen during fresh cycles. If this continues, electively freezing all of a patient’s embryos for a later frozen embryo transfer may become a viable alternative to fresh embryo transfer, as it may eliminate the risks of ovarian hyper-stimulation syndrome and high order multiple pregnancy.