Frozen Embryo Transfer

Frozen Embryo Transfer Frozen embryo transfer (FET) is an innovative technique used to increase your--Read Below


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Family Clinic provides various fertility and child care services

  • Monday - Saturday (WOMEN)
    10:00 AM - 9:00 PM
  • Monday - Saturday (CHILD)
    10:00 AM - 5:00 PM
  • Sunday (Women's timing)
    10:00 AM - 4:00 PM


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Frozen Embryo Transfer

Frozen Embryo Transfer

Frozen Embryo Transfer

Frozen embryo transfer (FET) is an innovative technique used to increase your chances of becoming pregnant. To better understand FET, it helps to take a brief look at in vitro fertilization (IVF). During this procedure, egg cells are surgically removed and are fertilized by sperm collected from the patient's partner or a donor. Once fertilized, the embryo can immediately be transferred to the woman's uterus. This procedure is also known as fresh embryo transfer, and most women undergo induction of ovulation to further increase the chances of conception.

Using frozen embryo transfer, the embryos are cryopreserved in a process called vitrification, a process of flash freezing that prevents crystallization. When a woman experiences ovulation naturally, the frozen embryo can be thawed and placed in the uterus.

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.

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 Family Clinic, 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

  1. Medicines and Drugs in a Frozen Embryo Transfer FET Cycle
  2. GnRH agonist (such as Lupron) is given, either midluteal (day 21) or overlapping with a birth control pill.
  3. Down-regulation is confirmed by ultrasound and blood tests.
  4. 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.
  5. 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.
  6. Estrogen and progesterone is continued in the luteal phase.
  7. 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.
  8. If pregnant, estrogen and progesterone are continued until about 10-15 weeks of pregnancy and then weaned off.

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

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.