Cryopreservation of embryos is a method that allows them to remain viable for several years with the preserved ability to divide after thawing. The cryopreservation procedure is performed by treating embryos with liquid nitrogen. In this article we will consider the features of the freezing procedure, their types, as well as the specificity of cryoprotective embryos in the uterine cavity during in vitro fertilization .
Technology of embryo freezing
There are 2 methods of freezing embryos: vitrification and "slow freezing". The technology of "slow freezing" is considered obsolete and has ceased to be applied in many clinics. It consists in moving the frozen embryos into a straw with a cryoprotectant, then freezing water is produced. Freezing the embryo protects it from ice, but can lead to its dehydration. This reduces the number of embryos that are able not only to survive, but also to retain the ability to divide and differentiate.
Vitrification of embryos is a more modern technique, which consists in treating them with liquid nitrogen, while the water that they contain is converted into jelly.
The equipment for cryopreservation is quite expensive, especially the one used for "slow freezing". The shelf-life of frozen embryos should not exceed 5 years.
Transfer of embryos after cryopreservation
The embryo, which came from a cold before it is placed in the uterus, must be prepared. To do this, they are thawed at room temperature and treated with a special solution that will help the embryo to retain its properties. The transfer of thawed embryos is carried out through a special catheter, which is inserted through the cervical canal into the uterine cavity.
We examined the existing technologies of embryo freezing, as well as the procedure for replanting frozen embryos. Cryopreservation of embryos makes it possible to re-insert if there is no pregnancy after the first procedure.