Embryo Freezing

What are the advantages of embryo freezing?

We have a very successful cryopreservation program for surplus embryos. We, currently, only freeze on Day 5 or 6 (5-6 days after OPU). Following thawing, the survival rate is around 98-100% and our pregnancy rates in frozen embryo replacement (FER) cycles is comparable to fresh Day 5 ET cycles.

A FER cycle has several advantages, including i) the live birth rates are at least as good as those of fresh cycles; ii) medications used to prepare the cycle is more friendly when compared to a fresh cycle; iii) no need for an oocyte-pick-up procedure; iv) since 1 embryo is transferred in the majority of cycles twin pregnancy is avoided given the high maternal and neonatal risks associated with multiple pregnancies.

How much is the chance of Success in procedure of Frozen Embryo Replacement (FER) Cycle?

We use vitrification method for freezing surplus embryos, which is currently the state-of-art method for freezing. Vitrification has been a breakthrough in IVF, given the very high (around 98-100% at our center) survival rates following thawing. The live birth rate in FER cycles is at least as good as those attained in fresh embryo transfer cycles. Even the live birth rates in FER cycles might be a little bit higher due to the lack of any detrimental effect of stimulation on the inner lining of the uterus in fresh cycles.

How the patient is prepared for the frozen embryo replacement cycle?

There are different protocols that may be employed for preparation of the inner lining of the uterus for a FER cycle. Those are;

• Completely natural cycle This protocol is only performed in women with regular cycles. The only drawback of this protocol is the necessity of frequent trans-vaginal-ultrasonography and blood monitoring.

• Artifical cycle without suppression. With menses oral estrogen pills Estrafem) and, thereafter, (intramuscular progesterone are started and embryo transfer is scheduled accordingly.

• In pre-implantation genetic screening/testing (PGS/PGT) cycles, we do not perform fresh embryo transfer and freeze all the biopsied blastocysts. The survival rate following vitrification is similar to non-PGS/PGT cycles and is around 98-100%.

• Rarely, with space occupying lesions in the uterine cavity, such as big polyps, we may go to freeze-all. In such cases, following hysteroscopic removal of such polyps, we may plan an immediate FER cycle, based on the availability of the patient.