FROZEN EMBRYO TRANSFER
Used in the IVF/ICSI method, this technique consists of transferring fertilized, cryopreserved, and subsequently thawed embryos into the uterus.
Cryopreservation, in turn, is a process for preserving biological tissues (sperm, eggs, and/or embryos, as in this case) at a temperature of -196 ºC with the help of tanks filled with liquid nitrogen (a method known as vitrification). Embryos preserved in this way can later be thawed for transfer, with a very high survival rate (close to 98%).
Embryos may be cryopreserved for fertility preservation purposes; when there are surplus embryos, that is, when the number of high-quality embryos exceeds the number that can be transferred; or when embryo transfer cannot be performed for some reason during that cycle (OHSS, for example), requiring all embryos to be frozen (freeze-all).
It is important to remember the possibility of embryo donation for families who wish to undergo IVF but are unable to produce eggs. Patients who no longer need their embryos may anonymously donate them through the fertility clinic itself;
As with embryo donation, if there is no longer any need or interest in them, they may also be donated to stem cell research institutions. In this case, the embryos must have been cryopreserved for more than 3 years, in accordance with the law.
