A frozen embryo transfer (FET) is when a vitrified embryo, created through IVF, is thawed and transferred to the uterus. FET cycles often replace a fresh embryo transfer, which would occur 5 days after their egg retrieval. FET is performed if the couple is genetically testing their embryos, which requires embryo cryopreservation.
Frozen embryo transfers are also used when a fresh embryo transfer is unsuccessful. Upon egg retrieval in a fresh transfer cycle, several eggs are often collected, frozen, and stored for use at a later point as part of a frozen embryo transfer. This saves the patient the time, stress, and cost of having to go through another egg retrieval procedure during a subsequent IVF cycle.