A frozen embryo transfer is a type of IVF treatment wherein a cryopreserved embryo, created in a full cycle of IVF is thawed enough to soften it up and hence transferred to the uterus of a woman. The embryo which has been cryopreserved might well be from a woman, who had previously gone through a typical IVF cycle or it can also be a donor embryo. In case a donor embryo gets used, then obviously that embryo is neither related to the woman nor to her partner.
On most occasions, a frozen embryo transfer takes place when there are extra embryos available after a normal IVF cycle. The usually preferred option is to have a fresh transfer.
Reasons behind Choosing To Have a Frozen Embryo Transfer-In Vitro Fertilization Cycle (FET - IVF)
One can choose to go for an Frozen Embryo Transfer cycle if:
A fresh IVF transfer fails and a woman has embryos which are cryopreserved: IVF Treatment cycle can result in the emergence of one or more than one embryo. The safe option is to get only one embryo transferred or a maximum of two at a time. In order to ensure complete reduction of risk, certain doctors even recommend women to go for Elective Single Embryo Transfer, especially for those with a good prognosis.
On certain situations, an IVF cycle can result in extra embryos. Most women opt to freeze or cryopreserve their extra embryos. For instance, a woman gets five embryos. Now, lets presume that a doctor recommends a woman to go for elective single embryo transfer. This would ensure that only one out of the five embryos will get transferred, whereas the remaining four embryos will be cryopreserved. It can well happen that one embryo transfer does not lead to successful pregnancy, then in that scenario, there would be a couple of options: a) A woman can go for another fresh complete IVF cycle or b) She can transfer either one or two of her embryos which were previously cryopreserved.
A woman may want to give her IVF conceived child a sibling: If a fresh embryo transfer results in pregnancy, then through the last example, given above, a woman can have four embryos, which are waiting to get cryopreserved. Cryopreserved embryos can be on liquid nitrogen for an indefinite period of time. Cryopreserved embryos can be used for second child.
The embryos are screened genetically: There are two assisted reproductive techniques in the form of Preimplantation Genetic Diagnosis and Preimplantation Genetic Screening , which ensure embryos to get screened for any kind of specific disease or defects. This is carried out through a biopsy of the embryo on the 3rd or on the 5th day after fertilization and after the egg gets retrieved. On certain situations, the results get back in time for performing a fresh embryo transfer. In case the biopsy or genetic test result is complex and more time gets consumed, in that case all those embryos whose biopsy were taken get cryopreserved.