During the IVF process, usually many embryos are produced. Also, sometimes we need to test the embryo genetics before transfer. So, we provide embryo freezing to preserve the embryos for future use. Recent SART and CDC reports indicate that, the success pregnancy rate of frozen embryo transfer is like the fresh embryo and even better with genetic testing. Of course, success rates depend on many factors like mother’s age, embryo quality and cause of infertility.
Currently, the embryo freezing method which we use is vitrification. The way to perform vitrification is to add some cryoprotectants (Ethylene glycol, DMSO, Glycerol, propanediol. . .etc.) to the embryo culture media. Cryoprotectants can help to ovoid ice crystal formation during freezing process. Once the embryos vitrified, they are stored in liquid nitrogen, they are safe and sound and can remain for long time.