The frozen embryo transfer (FET) is a process in which cryopreserved or frozen embryos from a previous cycle are thawed and transferred back into the uterus in order to achieve a pregnancy.
During a FET cycle, a baseline ultrasound is performed when the patient gets her periods. If the scan looks normal, estrogen supplementation is started.
Estrogen supplementation helps in improving the endometrial lining. It is continued until we get a lining of 9 -10mm. Serial ultrasound scans are performed to check the endometrial lining. The monitoring during a FET cycle is significantly less than during a conventional IVF cycle. When the endometrial lining is good, progesterone support is added and embryo transfer is scheduled. The number of days of progesterone prior to transfer depends on the day of freezing of the embryos.
Success with fresh and frozen cycles is equally good. Some studies have shown that frozen embryo transfer can give a slightly better chance.