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Embryo Freezing

Frozen Embryo Transfer

A frozen embryo replacement (FER) is a type of IVF treatment where a cryopreserved embryo created in an IVF cycle is thawed and transferred to the uterus.

FER typically uses “extra” embryos a couple has from a previous conventional IVF cycle. A cryopreserved embryo can also be a donor embryo.

There are many possibilities with donor embryos, including embryo donation, the donation of an egg that can be inseminated with a partner’s sperm, or the donation of sperm that can be inseminated into a partner’s egg.

A “fresh” embryo isn’t necessarily preferred, but it can be helpful in some cases. For example, in younger patients when there is no suspected chromosomal issue or in older patients who have embryos that didn’t make it to testing in the lab they might have a better chance in utero without testing.

FER is recommended (also referred to as a “freeze all” approach) where a fresh transfer is not possible In case of risk of hyperstimulation or if the endometrium is not favorable. In such cases, all embryos are cryopreserved and transferred in a FER cycle in the next month or so.