The field of assisted reproductive technology is advancing day by day with newer options and treatments being discovered. The area of Cryopreservation (freezing) is one of them. Till date it has been possible to freeze sperms and fertilized embryos for years. It involves treating these gametes with special cryoprotectants to enable them to withstand the freezing and thawing process using a cryofreezer and then plunged into liquid nitrogen at -196C. The world's first baby born from frozen embryos was pioneered by Dr. John Leeton of Queen Victoria hospital, Australia in the year 1984. Since then several births have taken place worldwide.
Cryopreservation (freezing) can provide an increased cumulative pregnancy rate while decreasing the risk of multiple gestations and the risk of ovarian hyperstimulation syndrome. Cryopreservation also provides an additional chance of pregnancy in a treatment cycle which does not involve full ovarian stimulation and oocyte retrieval.
Cryopreservation involves
# Initial exposure to cryoprotectants
# Cooling to sub zero temperature
# Storage and thawing
# Dilution and removal of cryoprotectants
> An egg bank facility would make donor programmes a cheaper option when there will be no need for synchronizing the treatment cycle. Just like a sperm bank women will get to use oocytes frozen from potential donors.
> If a couple opt to step out of a relationship they still would have a legal tangle regarding ownership of frozen embryos. Hence freezing individual gametes would save trouble in decision making.
Cryopreservation (freezing) can provide an increased cumulative pregnancy rate while decreasing the risk of multiple gestations and the risk of ovarian hyperstimulation syndrome. Cryopreservation also provides an additional chance of pregnancy in a treatment cycle which does not involve full ovarian stimulation and oocyte retrieval.
Cryopreservation involves
# Initial exposure to cryoprotectants
# Cooling to sub zero temperature
# Storage and thawing
# Dilution and removal of cryoprotectants
The goal is to maintain the structural integrity of the cell (total protection of the cell) throughout the Cryopreservation procedure
INDICATIONS FOR OOCYTE CRYOPRESERVATION
# Surplus oocytes obtained during retrieval as in cases of Ovarian hyper stimulation syndrome
# Those at risk of losing ovarian function due to pelvic disease like severe endometriosis and infections.
# Those who wish to delay childbearing
# Donor programme where there is a possibility of oocyte banks.
# Single mothers/divorcees
# Premature ovarian failure
# Those women who are likely to lose ovarian function following cancer chemotherapy or radiation
# Those at risk of losing ovarian function due to pelvic disease like severe endometriosis and infections.
# Those who wish to delay childbearing
# Donor programme where there is a possibility of oocyte banks.
# Single mothers/divorcees
# Premature ovarian failure
# Those women who are likely to lose ovarian function following cancer chemotherapy or radiation
ADVANTAGES
The advantages of exclusively freezing oocytes are:
1. No legal concerning single gamete freezing. Just like sperms being frozen for a man, a woman may be entitled to freeze her oocytes for later use. This would be of help in the following scenarios:-
> Women who wish to postpone childbirth, either for educational or career demands or the absence of a stable relationship.
> An egg bank facility would make donor programmes a cheaper option when there will be no need for synchronizing the treatment cycle. Just like a sperm bank women will get to use oocytes frozen from potential donors.
> If a couple opt to step out of a relationship they still would have a legal tangle regarding ownership of frozen embryos. Hence freezing individual gametes would save trouble in decision making.
2. To assist siblings in familial cases of premature ovarian failure to have a child using the donated oocytes from the same family.
3. Risk of losing ovarian function due to pelvic disease or following surgery
4. Multiple pregnancies can be avoided
5. Useful in cases of OHSS
6. Moral, ethical and legal problems do not exist like how it does for embryos.
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