Thickening the Lining
This first phase on preparing for an FET is Estrogen “supplementation.” Estrogen acts to thicken the uterine lining, similar to how estrogen produced by a developing egg follicle does during a normal menstrual cycle. After approximately 8-10 days, the woman will come in for a lining check and be instructed on the next phase of the FET preparation. Lining "receptivity" After your lining check, one will typically continue their estrogen regimen and be instructed to add the progesterone medication in a few days. Progesterone helps the uterine lining receptivity to embryo implantation. Typically progesterone is started on days 11-13 from the beginning of the estrogen protocol and sets the actual embryo transfer procedure in motion and determines when your embryo(s) will be thawed and transferred.
Cleavage (Day 3) embryos will be transferred 4 days after the start of progesterone.
Blastocyst (Day 5 . . . or 6/7) embryos will be transferred 6 days after the start of progesterone. Frozen Embryo Transfer
Much like a fresh transfer or pap smear, a frozen embryo transfer does not require any anesthesia and is usually painless.
The thawed embryos are loaded into a catheter with a small amount of transfer media which is then passed through the cervix and deposited into the uterus.