What it is?
After the process of in vitro fertilization(IVF) and intracytoplasmic sperm injection (ICSI), several good quality embryos may remain unused. Instead of disposing them, these ‘extra’ embryos can be frozen for future use. Also called embryo banking and embryo cryopreservation.
Who can do it?
- Couples who want to have a baby at a later stage.
- Couples for whom the fertility treatment does not work in the initial cycle.
- For women who want to have children after certain medical treatments such as radiationtherapy or chemotherapy
How we do it?
- After fertilization, good quality embryos are selected.
- These are mixed with a “cryoprotectant”, which will protect them from formation of ice crystals.
- There are two ways of freezing and preserving the embryos: slow programmable freezing and vitrification
- Slow freezing method: The embryos are frozen slowly, in stages. The cryoprotectants are added to the embryos over 10 to 20 minutes. Then the embryos are slowly cooled over two hours in a machine that lowers the temperature minute by minute. Once frozen, the embryos are stored in liquid nitrogen at -196.1°C.
- Vitrification: This is a rapid freezing technique that uses higher strengths of cryoprotectants. These are mixed with the embryos. Strong cryoprotectants can hurt the embryos. To prevent this, the embryos are quickly placed into the liquid nitrogen. This process changes them into an almost-solid state, like glass. In this state, ice is unable to form.
When required, the embryos are slowly thawed and soaked in special fluids to remove the CPAs. This also restores the internal water balance.
When is embryo cryopreservation done?
Embryos are often frozen from 1 to 6 days after they are made.
How long can embryos be stored?
Embryos can be stored for many years.Successful pregnancy has been achieved from embryos frozen for more than 10 years. Check with your doctor to confirm what time limit is right for you.The duration of storage does not harm the success rate of IVF.
Is there a risk to the baby born using frozen embryos?
Studies show that there is there is no additional risk of birth defects when frozen embryos are used compared with normal births. Thus, freezing and thawing embryos does not harm the baby.