Frozen embryo transferThe highest success rates in Europe
A frozen embryo transfer (FET) is a cycle where frozen embryo from a previous fresh IVF cycle is thawed and transferred into a woman's uterus.
Why do we freeze embryos?
During a fresh IVF cycle, sometimes we can create more than one embryo. Usually, we transfer no more than two embryos, as there is always risk of multiple pregnancies, and recommend to freeze the others. But if you’ve experienced a failed IVF cycle and want to try again, want to avoid ovarian hyperstimulation syndrome (OHSS), or want to continue building your family, you might be considering a frozen embryo transfer (FET) IVF treatment. Frozen embryos can remain frozen for up to 10 years, though freezing techniques and quality of the embryos influence the survival rate of the embryos.
At our clinic we use ultra-rapid embryo cryopreservation (vitrification), which freezes the embryo rapidly (about 60,000 times faster than was the case using the older “conventional” slow freezing approach). The slow freezing approach resulted in the formation of intracellular ice that damaged the embryos, resulting in a low survival rate. Thawed embryos had significantly decreased implantation potential. Vitrification method avoided intracellular ice formation and enabled 90% survival rate with implantation and pregnancy generating potential at least as good as in fresh embryos.
There are different protocols for frozen embryo transfer cycles. It can be done in your natural cycle without any stimulation in case you have regular ovulation. Or it can be "controlled" frozen embryo transfer cycles with hormone replacement therapy in case your hormones are not produced correctly.
During the frozen embryo transfer cycle you will undergo several ultrasound scans to measure the thickness of utrerus lining and take Estradiol valerate in appropriate for you dose after previous down-regulation, prescribed by your doctor. When the endometrium has at least 8 mm thickness, progesterone is started and embryo transfer is planned 3-6 days later. Estrogen and progesterone is continued in the luteal phase. Pregnancy testing is done 14 days after transfer.
In accordance with the newest research data the success rates of an FET cycle are nearly the same as fresh IVF cycles.