Frozen Embryo Transfer, FET Cycles After IVF
Page author Richard Sherbahn MD
There has been a recent trend away from traditional "slow freezing" technology that has been used since the 1980's. The newer vitrification method for IVF embryo freezing is becoming a much more widely used technology.
In our clinic vitrification of "spare" embryos after IVF shows excellent "post-thaw survival" and pregnancy success rates after transfer.
How are frozen-thawed embryo transfer cycles managed?
There are different protocols for FET cycles. That is true for both "natural cycle" FETs and for "hormone replacement cycle" frozen-thawed embryo transfers.
At the Advanced Fertility Center of Chicago, we use hormone replacement cycles because they have better success rates. However, some clinics offer a natural cycle FET approach. Success rates are higher with hormone replacement, or "controlled" FET cycles.
Hormone replacement cycle, controlled FET
Medicines and Drugs in a Frozen Embryo Transfer FET Cycle
- GnRH agonist (such as Lupron) is given, either midluteal (day 21) or overlapping with a birth control pill.
- Down-regulation is confirmed by ultrasound and blood tests.
- Estradiol valerate 2 mg twice daily (orally) is started after the period. This dose may need to be increased after monitoring of the uterine lining thickness.
- When the endometrium has a "good" thickness, progesterone is started (intramuscular shots, or a vaginal product).
- Embryo transfer is planned for 3-6 days later - depending on the stage of development of the embryos to be transferred.
- Estrogen and progesterone is continued in the luteal phase.
- Pregnancy testing is done 9-14 days after transfer - depending on the stage of development of the embryos replaced and the preferences of the fertility clinic.
- If pregnant, estrogen and progesterone are continued until about 10-15 weeks of pregnancy and then weaned off.
There are other protocols that use transdermal estrogen patches, intramuscular shots of estrogen, vaginal estrogen administration - and various routes and products for progesterone support.
Pregnancy success rates with FET - frozen embryo transfers:
Success rates for frozen embryo transfer cycles vary considerably by the program handling the case. Some programs have low pregnancy and live birth from their frozen embryo transfer cycles while other IVF programs have live birth rates of over 50% per transfer procedure in women under 35 for frozen-thawed transfer cycles.
- As more IVF programs vitrify rather than slow freeze the spare embryos, FET success rates across the US should improve significantly
- Our success rates for frozen transfer cycles
There is no good way to know about the pregnancy success results at an IVF program other than:
- Check the CDC and / or SART results for the specific IVF program for frozen embryo transfers
Links to the annual SART and CDC success rate reports
- Ask very specific questions of your physician and make sure that you get a clear answer.
Ask your doctor for:
- The percentage of embryo thaw cycles that resulted in a transfer. Some thaws might result in degeneration of all of the embryos - therefore, no transfer is done.
- The live birth rate per transfer procedure for frozen-thawed embryos.
Blastocyst implantation in an FET cycle
Embryo implantation after frozen blastocyst transfers (FET) can be slightly delayed compared to that seen with fresh blastocyst transfer. This is sometimes referred to as "late implantation", or delayed implantation.
However, the embryo implantation process is not different enough to warrant changing the timing of the blood pregnancy test. Frozen blastocyst transfers should have hatching and the beginning of implantation by about 1-3 days after the FET.
Early pregnancy detection following blastocyst transfer is possible with a sensitive blood assay for HCG hormone by about 9 days after a fresh or frozen blastocyst transfer.
A urine HPT (home pregnancy test) can be done by 10 to 12 days after blastocyst transfer (fresh or frozen), if it is a sensitive, high quality test kit.
We currently charge:
- $800 to freeze embryos (any number of embryos)
- $4000 for a complete frozen embryo transfer, FET cycle
- Our prices for IVF