Cryopreservation or cryoconservation is a process where organelles, cells, tissues, extracellular matrix, organs or any other biological constructs susceptible to damage caused by unregulated chemical kinetics are preserved by cooling to very low temperatures (typically -80 °C using solid carbon dioxide or -196 °C using liquid nitrogen). At low enough temperatures, any enzymatic or chemical activity which might cause damage to the biological 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.
When IVF is done multiple embryos are formed. Not all of them can be transferred at one go. Only two or three embryos are transferred at one time.
The surplus embryos are cryopreserved.
There are straws available for freezing. Usually 3 embryos are frozen per straw.
The advantage of doing this cryopreservation
Woman does not have to undergo the whole process of IVF again in case the cycle fails. We can do frozen-thaw embryo transfer. (FET) In FET, the uterine lining is prepared by giving oral hormonal medications from the 2nd day of the cycle. By doing so, endometrium becomes very receptive for embryos.
The embryos are transferred between 18 to 22 days depending upon the size and vascularity of endometium.
There are few more reasons to do embryo /oocyte freezing...
- The lady is professionally busy and unable to plan pregnancy.
- If woman is detected with cancer, before undergoing chemo or radiotherapy.
If she is already married can undergo IVF and do Embryo Freezing.
If she is not married, she can undergo IVF upto oocytes retrieval and can do Oocyte Freezing.