Egg freezing or oocyte cryopreservation is not a new technology; it has been around for many years and the first birth from frozen eggs was recorded in 1986. Egg freezing involves the process of extracting the eggs from the women, freezing them and then storing them for future use. It helps the women by suspending the biological clock from ticking.
Who to opt for egg freezing?
Nowadays, many women suffer from cancer, and the treatment for cancer involves chemotherapy and radiation which are toxic for the eggs and they harm the fertility, so there is an option of freezing the eggs before starting the treatment and having the freedom to have biological children in future. Couples undergoing in vitro fertilization, sometimes have to freeze the eggs if the partner is not able to produce sperms on the same day the eggs are retrieved. Some people prefer to freeze the eggs as compared to embryos for various reasons during their IVF treatment. Women who are busy with their career or who marry late prefer to freeze their eggs at younger age so that they can reproduce later and they do not have to worry about their biological clock running out of time. Before going in for egg freezing procedure the doctor will run a few tests which include ovarian reserve testing to determine the quality and quantity of the eggs, ultrasound of the ovaries to get the complete picture of the functioning of the ovary. They are screened for infectious disease like HIV, hepatitis B or C because infectious eggs are stored separately from other eggs.
Ovulation induction :
The treatment starts with several weeks of hormone injections to stimulate the ovaries to produce more eggs and during this time there will be many follow ups at the clinic for ultra sound to keep track of the eggs maturing in the ovaries.
Egg retrieval :
During the procedure of egg retrieval the patient is sedated. An ultrasound probe is inserted through the vagina to identify the follicles and then a hollow needle is inserted through the vagina to retrieve the eggs by suction method. After this procedure the patient might experience cramps and a feeling of fullness or pressure as the ovaries are enlarged.
Immediately after the eggs are harvested, they are frozen. The eggs are the largest cell of our body and contain large amounts of water, so when they are frozen the ice crystal which are formed can harm the integrity of the cell, to prevent this egg has to be dehydrated before freezing by using cryoprotectant. It replaces most of the water in the cell and prevents the ice crystals from forming. Eggs are frozen by using slow-freezing method or flash-freezing method called vitrification. In slow freezing method low concentration of cryoprotectant is initially used and as the temperature reduces there is decline in the metabolic rate of the eggs and then higher concentration of cryoprotectant is used. This method is used to protect the eggs from exposure to toxins in the cryoprotectant. Freezing by vitrification is much faster and it uses higher concentration of cryoprotectant and the result is glass like solid egg devoid of ice crystals. Ice formation inside and outside the eggs on cooling, during cryostorage or on warming are eliminated by using vitrification. There is higher rate of survival and development in vitrification as compared to slow freezing and so it is being successfully used in IVF treatment.
Nowadays, when the eggs are thawed the sperm is directly injected into it with a needle as opposed to letting the sperm penetrate the egg naturally by keeping it around the egg in the dish. This fertilization procedure is called intracytoplasmic sperm injection [ICSI] and it is also used in IVF. Age plays a vital role in chances of becoming pregnant because the older you are at the time of freezing the eggs lesser is the chance for having a live birth in the future. There is a higher rate of pregnancy when fresh or frozen embryos are used as compared to frozen eggs.
Egg storage :
After the eggs are frozen they are immediately stored in liquid nitrogen containers for safe keeping till they are transported to a long term cryobank storage facility. These cryobank facilities are licensed places which have the necessary technology to store the frozen eggs for a long duration and this is called cryopreservation.
Duration of cryopreservation :
The eggs are normally stored for the period of ten years. Only in certain cases the period is extended and that is done under the guidance of the clinician.
Cost of egg freezing:
The cost of the egg freezing procedure is not cheap and even the cost of fertility medication has to be kept in mind. You will also have to consider the cost of the egg storage facility.