Cryopreservation or cryoconservation is a process where cells, whole tissues, or any other substances susceptible to damage caused by chemical reactivity or time are preserved by cooling to sub-zero temperatures. At low enough temperatures, any enzymatic or chemical activity which might cause damage to the material in question is effectively stopped.
Cryopreservation methods seek to reach low temperatures without causing additional damage caused by the formation of ice during freezing. Traditional cryopreservation has relied on coating the material to be frozen with a class of molecules termed cryoprotectants. New methods are constantly being investigated due to the inherent toxicity of many cryoprotectants.
Cryopreservation is used in infertility programs to freeze and store sperm, eggs or to freeze “leftover” embryos from an invitro fertilization cycle
There are 2 methods currently used for freezing in IVF labs
- Slow freezing
- Vitrification (ultra-rapid freezing)
Embryo Freezing During IVF or ICSI Cycles
A new technique of embryo freezing was introduced few years ago, named VITRIFICATION. In view of this technology advancement, the fertility centre might decide to freeze all your embryos and transfer them in the next cycle in the following situations:
- More than 20 eggs (hyper stimulation).
- Endometrium (uterus lining) thin or < 7 mm in thickness.
- Less eggs and embryos (less than 3 of grade 1).
- Patients with low AMH and poor responders (pooling of embryos).
- History of previous miscarriage.
- History of previous ectopic pregnancy.