Cryopreservation is a group of processes of preparation, freezing, and storage human gametes and embryos before their implantation in extremely low temperatures, usually in liquid nitrogen. It is a clinical procedure performed in the Sector for assisted reproduction in Dr. Shterev Hospital. This technique allows the freezing and storage of embryos which have not been transferred into woman’s body during the IVF/ICSI procedure. The aim is to use the cryopreserved embryos in a future period without performing new controlled ovarian hyperstimulation and only preparing the endometrium for embryo transfer.

The development of a good program for cryopreservation and thawing is of great importance. Thus more embryos can survive the procedure which leads to higher pregnancy rate.

Not all embryos have the necessary quality to be cryopreserved and kept. Embryologist chooses only those with the potential to survive all the process. The assessment could be made only by an expert and after the observation and analysis of the whole period of embryo growth and development.

After the fertilization, the embryos for cryopreservation are selected amongst those at blastocyst stage at day fifth. They are put in cryo containers and unique medium (quality certified cryo protectors approved for use in ART procedures) and are kept in under -196C temperature in liquid nitrogen.

Embryo survival does not depend on the period of storage but the quality of the cryopreservation procedure. In Regulation 28 for ART (issued by the Ministry of Health in 2007, last amendment in 2014) there is a recommended storage period which is five years.

When is advisable?
Embryo cryopreservation is advisable in cases of:
• Ovarian Hyperstimulation Syndrome (OHSS), when embryo transfer in the cycle as the controlled ovarian hyperstimulation is not advisable.
• If the endometrium is not ready for embryo implantation in the current cycle
• Remaining embryos with good quality after the embryo transfer. So after the fresh embryo transfer, they could be used if there is no pregnancy, or for reproduction after a successful procedure. 
• To reduce the risk of multiple pregnancy.
• Need to keep the fertility capacity for a future period.

What are the steps for embryo freezing in Dr. Shterev Hospital?

Step 1: Performing an IVF/ICSI procedure and producing embryos with good quality (only those can be cryopreserved).

Step 2:  Discussing with patients the quantity and quality of the embryos which could be cryopreserved

Step 3: Filing an Informed Consent for cryopreservation and storage of embryos, including the desired keeping term

Step 4: Cryopreservation and storage of the embryos

Step 5: After expiring the keeping term and if the women did not indicate extension, the embryos should be destroyed.

The innovations and progress of modern medicine give a chance to a lot more couples for conceiving and giving birth to a healthy baby. By virtue of the physicians, embryologists, and biologists every patient has his trusted team, with which help passes through the hard path to the big dream.