Embryo cryopreservation is the process by which surplus embryos resulting from IVF /ICSI cycle are frozen for future use . Traditional freezing technique has the disadvantage of formation of ice crystals which can cause embryo injuries . We use the vitrification method. In vitrification water molecules in an embryo are removed and replaced with a cryoprotectant . The embryos are then plunged directly into liquid nitrogen . This sudden & drastic freezing creates a glass transition known as glass state . This reduces formation of ice crystals as in slow cryofreezing. Once frozen embryos are contained within labeled sterile straws which are immersed in liquid nitrogen . These can be safely stored like this for years.
Why do we need vitrification?
Vitrification is used to store your extra embryos and to avoid repeated ovarian stimulation.