A Complete Guide to Cryopreservation

August 30, 2022

A Complete Guide to Cryopreservation

Cryopreservation is the process of freezing and preserving the embryos, eggs or sperm for future use. The unused embryos (fertilized eggs) or unfertilized eggs during an in vitro fertilization treatment involving intracytoplasmic sperm injection (ICSI) are frozen as a primary step in embryo or egg cryopreservation, and used later after thawing in IVF. Couples generally choose cryopreservation for reasons such as:

  • not wanting to conceive initially; instead, have a backup plan of preserving the embryos at a young age and use them later to become pregnant
  • having a condition that may affect your fertility. The condition includes autoimmune diseases, gender diversity and sickle cell anemia
  • starting medical treatment for cancer or any other sicknesses that have an influence on your ability to become pregnant. Here undergoing chemotherapy or radiation can affect fertility. 
  • undergoing IVF, so choose egg or embryo freezing for ethical reasons
  • saving money on the IVF cycles you would be undergoing in future

How Is Cryopreservation Process Performed?

Freezing eggs or embryos is challenging for a cell mostly contains water and on freezing, ice crystals are formed, which can harm the cell wall, as well as the tiny structures within the cell. To protect the embryo or cell when freezing, cryoprotectant, a special substance, is used. There are two ways of freezing embryos or eggs.

Also, Read: Who Are the Right Candidates for Egg Freezing

Slow Preserving Method

The slow preservation process is done in stages. The embryos are initially placed in a sealed tube and cooled very slowly at 3° Celsius or less than that per minute. During the cooling process, cryoprotectant is added by slowly increasing its strength. The embryos are then cooled in a machine stage by stage lowering the temperature every minute. The process continues until the temperature reaches -196° Celsius. This is when the embryos are stored in liquid nitrogen.

Vitrification Method

Vitrification is the latest technique that enables rapid freezing of the eggs or embryos at -196° Celsius. The embryos are kept in a solution having high concentration of cryoprotectant, and then placed in liquid nitrogen to instantly become vitrified or glass-like substance. Vitrification prevents the formation of ice crystals and thereby, increases the embryos’ chances of viability, quality and survival after thawing. 

Is Embryo Cryopreservation Safe?

Embryo freezing or cryopreservation is considered safe despite being the new pregnancy treatment process. Studies have shown successful pregnancy, as well as delivery using embryo cryopreservation. However, there are risks of a marginally higher chance of genetic abnormalities in the baby than those in the baby born from non-frozen embryos. There is not enough research conducted in regard to this, and therefore, the long-term effects are not known. It is better to consult a fertility specialist before deciding on embryo cryopreservation pregnancy.

How Should You Prepare for Cryopreservation?

The first thing to do is to find the right fertility clinic, which has specialists in reproductive medicine or reproductive endocrinologists. There is not enough information about pregnancies using frozen embryos or eggs, and therefore, a clinic’s success rate largely depends on several factors, especially a woman partner’s age. The cost for cryopreservation is high owing to the number of stages you need to go through. Other than the charges for each stage, there is an annual storage fee too.

You need to undergo screening for the embryo freezing process and they are:

Ovarian reserve tests: These tests include follicle stimulating hormone (FSH), anti-Mullerian hormone (AMH), estradiol and ovarian antral follicle count to determine the egg supply and the quantity and quality of the eggs. You are required to have these tests on the third day of the menstrual cycle. To have a complete picture of the ovary, an ultrasound scanning and a blood test is performed by a physician. 

Screening for infectious diseases: You need to ensure that there is no chance of any infectious diseases such as hepatitis B and C and HIV via screening.

What is the Success Rate of Embryo Cryopreservation after Thawing?

Research shows that after cryopreservation and thawing, the success rate of embryos is relatively high. It further suggests that the women using thawed embryos would deliver healthy babies. A comparative study conducted in 2016 revealed that there is not any increase in developmental abnormalities in babies. Long-term research is still needed to throw more light into this.

How Long Can You Have the Frozen Embryos Stored?

It is presumed that the embryos in liquid nitrogen can be stored any number of years if they are correctly frozen. The embryos that remain in -196° Celsius are not subject to any biological processes. Some studies have revealed successful pregnancies from frozen embryos, which have been stored for 10 years. Nevertheless, there is cost for freezing and storage, which in the long run will turn out to be expensive. This induces several fertility clinics in India to have their own rules on time limit and price for storing frozen embryos.

In conclusion, cryopreservation gives you option to become conceived or delay pregnancy.

Also, Read: Difference Between Egg and Embryo Freezing

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