FROZEN EMBRYO TRANSFER (FET)
FROZEN EMBRYO TRANSFER (FET)
When an individual or couple has frozen (cryopreserved) embryos, an FET cycle is planned to prepare the woman's uterus to receive the thawed embryos.
During the consultation you will discuss how the uterine lining is prepared to accept the embryos, and the recommended number of embryos to thaw and transfer. For your convenience, an appointment with our IVF Coordinator, Kori Garcia, RN, can follow the consultation where she will fully explain the steps of the cycle and select a date for the transfer.
The development of an optimal uterine lining (endometrium) in which the embryo can implant is a crucial step in the cycle. At TFC, we use a medically programmed plan to achieve this goal.
The woman takes birth control pills for 2-4 weeks to quiet the ovaries. When instructed, the pills are stopped and she begins medication (Estrace or Estradiol valerate) to stimulate the lining of the uterus to thicken. After 2 weeks of medication, an ultrasound of the uterine lining is performed to ensure an adequate endometrial thickness is developing before the embryos are thawed. Five days before the embryo transfer, vaginal progesterone gel is started to make the endometrium receptive to the embryo(s).
The embryo transfer procedure is the same as in an IVF cycle. The morning of the embryo transfer, the designated number of embryos are thawed. Approximately 80-90% of cryopreserved embryos survive the thawing process.
Under ultrasound guidance to ensure optimal placement, the embryo is transferred via a thin plastic tube (catheter) which is carefully guided into the upper part of the uterus and the embryo placed. The transfer is a painless procedure and the woman remains resting for 1/2 hour, after which she goes home. We recommend she rests at home through the next day before resuming her activities.
After the Embryo Transfer
The Estrace/Estradiol valerate and progesterone supplementation continue to enhance implantation and support an early pregnancy. Ten days following the embryo transfer a blood pregnancy test is performed. If the test is positive, ultrasound confirmation of a clinical pregnancy (presence of heart beat) occurs about 3 weeks later. Hormonal supplementation (Estrace/Estradiol valerate and progesterone) continue until the pregnancy can sustain itself at 12 weeks.
Endometrial “Scratching” is a procedure which is performed approximately 1 week before starting the Frozen Embryo Transfer (FET) cycle. It involves the insertion of a small pipelle (tube) through the cervix into the uterus and taking a small sample of endometrial tissue (uterine lining). This brief office procedure, is also known as an endometrial biopsy, or EMB. While not entirely understood, it is believed the “scratching” or disruption of the uterine lining releases growth factors that help improve embryo implantation in the subsequent FET cycle. This procedure may prove helpful for those who have failed IVF cycles and studies suggest it may increase pregnancy by up to 70% compared with no treatment.
Assisted Hatching is a common laboratory technique in which an embryologist uses a precise laser to make an artificial opening in the shell of the embryo to facilitate implantation by the embryo into the uterine lining. The hatching is performed immediately before loading the embryo into the transfer catheter. Assisted hatching is recommended for all cryopreservation cycles (Frozen Embryo Transfer and Egg Freezing).