The effect of cryopreservation on developing and improving the effectiveness of methods of assisted reproduction is gaining an increasing importance, with almost one fifth of births coming from cryopreserved embryos.
The cryopreservation by vitrification has become more and more popular in recent years. The vitrification process is the ultrafast cryopreservation of eggs and embryos, which prevents the formation of intracellular crystals. Also, it uses new generation cryoprotectants, substances which protect tissues from damage that may be caused by the process of cryopreservation. Rapid cryopreservation in conjunction with the high concentrations of cryoprotectants leads ova and embryos in the glassy phase. By avoiding the creation of intracellular crystals, cryopreserved oocytes and embryos are protected from possible damage during the process of thawing. The process takes just a few minutes.
Avoiding damage of eggs during the process of thawing, gave rise to the widespread use of the method of vitrification mainly for eggs’ cryopreservation. In recent years, via the vitrification of oocytes, each woman has the possibility to cryopreserve her eggs, which can remain in cryopreservation for a long time without any further impact on their quality and be used later, when wished.
Cryopreservation of oocytes via vitrification is of extreme importance and is widely applied in fertility preservation cases of oncology patients, for social reasons, in cases of women with premature menopause or poor responders, for creating donor egg banks and in cases of male partner’s azoospermia in the process of assisted reproduction.
The first children from embryos who were cryopreserved by vitrification, were born In the early 1990s. Since then, in the countries where vitrification is used, more than 1,400 children have been born, while our country is sixth in the world and third in Europe, concerning the number of children born via this method.
In our unit, the method of vitrification is used from the beginning of its operation, with great success. The ova and embryo survival rates as well as the pregnancy rates after embryo transfer of cryopreserved embryos are extremely high.