FET - Frozen Embryo Transfer
Frozen Embryo Transfer (FET)
You may do a frozen embryo transfer (FET) cycle, if you still have frozen embryos left from a previous IVF cycle and wish to use them. This may be after a delivery of a child, and you wish to come back and use your frozen embryos. It could also be after an unsuccessful IVF cycle, in which you have obtained additional embryos that were not transferred and frozen.
The benefits of a frozen embryo transfer (FET) over a fresh embryo transfer cycle include lower cost, less complex treatment (e.g. no surgical retrieval of eggs), less medication, and generally similar success rates.
The success rates of an FET are nearly the same as fresh embryo transfers after IVF cycles.
FET uses embryos at the blastocyst stage or embryos day 3 that have been frozen following a fresh cycle.
At day 1 of the period the patients are instructed to visit the doctor on day 2 or 3 of the period, and to begin estrogen therapy, to build the uterine lining (endometrium). At day 7 - 10 will be the 1st ‘lining check,’ or endometrial thickness check by vaginal ultrasound and when the endometrium reaches enough thickness (more than 7 mm), the patients are instructed to add in progesterone suppositories or tablets or injections. A frozen embryo transfer date is confirmed, and the patient presents for her frozen embryo transfer.
Estrogen and progesterone intake continues during the frozen embryo transfer until at least 14 days after the transfer where a blood pregnancy test is done.
Most patients will be on oral contraceptives (birth control pills) 1 month before their actual frozen cycle.
An average patient may have 4 appointments during the cycle or frozen embryo transfer. 1st one on the 2nd or 3rd day of the period for a baseline evaluation (blood tests and vaginal ultrasound), before her medications are started. 2nd appointment is on the 7th - 10th day of the period to evaluate the endometrial response to the treatment and to insure that the uterine lining is thickened. The 3rd appointment is during the mid-cycle (‘lining check’), to measure the thickness of the endometrium to see if it has reached enough thickness in order to start Progesterone intake and to schedule the day of the frozen embryo transfer. The 4th visit to the doctor is on the transfer appointment itself. The frozen embryo transfer is done without anesthesia and without any pain. It is done in the same way as the usual fresh embryo transfer.
Then 2 weeks later a blood beta HCG pregnancy test is done.