While in vitro fertilization (IVF) is an effective fertility treatment, it is common for more than one cycle to be necessary for pregnancy. One way to eliminate the emotional, financial, and physical burdens of multiple IVF cycles is to have the embryos frozen (cryopreserved). Frozen embryo transfer is the process of using embryos for IVF that were previously preserved.
Monitoring and Testing
When frozen embryos are used during IVF cycles, the ovulation induction and egg retrieval process are not necessary. This makes these cycles less expensive, requiring fewer stages than the initial cycle. However, the fertility specialist must closely monitor and control the progression of the woman’s menstrual cycle. The frozen embryo transfer procedure takes place at the time of ovulation, and frequent blood tests and ultrasounds are done during the first 10-15 days of the cycle.
Before a frozen embryo transfer, all causes of infertility are evaluated and appropriately treated, which is done to not overlook something that may interfere with the frozen embryo transfer procedure. A hysterosalpingogram (HSG) is done to assure the fallopian tubes are open and functional. In addition, blood tests are done to assess hormone levels.
At cycle baseline, clients must begin a sequence of 15-22 days of estrogen injections, which build up the uterine lining. After a lining check on day five or six, clients begin taking progesterone. These drugs are also continued through the the pregnancy until around the 10th week of gestation.
The Embryo Transfer Procedure
When the cycle reaches the correct phase, 2-4 frozen embryos are selected for transfer. The frozen embryo transfer procedure takes place just as with fresh embryos. A thin, flexible catheter is inserted into the uterus through the cervix. The embryos are then placed into the uterine cavity through the tube. The entire procedure takes less than 30 minutes and no sedation is necessary.
Benefits of Frozen Embryo Transfer
In addition to being less expensive, FET has many benefits. These include:
Less medication – Injectable stimulation medication is not required with FET. Instead, the client takes estrogen and progesterone to prepare the uterus for the embryo transfer.
No egg retrieval – Since eggs do not have to be retrieved, there is no anesthesia required, and clients do not have to go through this step of the IVF process.
Less stress – FET cycles are less stressful than fresh cycles because they eliminate the stimulation, egg retrieval, and egg development stages. In addition, clients select the day for their transfer in advance.
Chances of Success
Around 70% of embryos survive the process of freezing and thawing. However, once thawing is over, the healthy embryos are selected. The chances of successful implantation and pregnancy using frozen embryos is equal to that of transfer with fresh embryos. Embryos cultured in the blastocyst stage have a 30% higher pregnancy rate than early transfer embryos. Women 37 years and younger have a 50% delivery rate per frozen embryo thaw and transfer. This rate does decline as maternal age goes up, however.
Cost of Cryopreservation, Storage, and FET
For clients at our fertility center, cryopreservation and storage fees are included in the contract. For clients pay for IVF fees for treatment, initial embryo freezing and storage for one year is due at the time of service, which is around $2,000. The cost of monitoring, embryology, embryo thaw, transfer, and first pregnancy test run around $5,000.