Egg Freezing

What is egg freezing (ooocyte cryopreservation)?

Egg freezing, also known as oocyte cryopreservation, is a great advancement in technology allowing women to preserve their fertility and their eggs. These eggs, once removed from the body are frozen using special techniques and can be used to make babies by the process of  IVF when the woman desires.

Who are the women who should go in for egg freezing?

Oocyte cryopreservation is optimum treatment for the following groups oof women:

1.Women diagnosed with cancer who have not yet begun chemotherapy or radiotherapy. Chemotherapy and radiotherapy are toxic for oocytes, leaving few, if any, viable eggs. Egg freezing offers women with cancer the chance to preserve their eggs so that they can have children in the future.

2. Individuals undergoing IVF who object, either for religious or ethical reasons, to the practice of freezing embryos. Having the option to fertilize only as many eggs as will be utilized in the IVF process, and then freeze any remaining unfertilized eggs can be a solution. In this way, there are no excess embryos created, and there need be no disposition of unused frozen embryos, a practice which can create complex choices for certain individuals.

3. Women who would like to preserve their future ability to have children, either because they do not yet have a partner, or for other personal or medical reasons.

4. Women with a family history of early menopause have an interest in fertility preservation. With egg freezing, they will have a frozen store of eggs, in the likelihood that their eggs are depleted at an early age.

5. Egg freezing can also be beneficial for women who, for the purpose of education, career or other reasons, desire to postpone childbearing. Freezing eggs at an early age may ensure a better chance for a future pregnancy.

What is the process for takimg out the eggs for freezing?

The egg retrieval process for oocyte cryopreservation is the same as that for in vitro fertilization. This includes ten to fifteen days of hormone injections that stimulate ovaries to grow multiple eggs.  The eggs are subsequently removed from the body by transvaginal route. This ensures that there is no cut anyhere on the body. The procedure is usually conducted under anaesthesia which makes it a totally painless procedure. The eggs collected are immediately frozen.

How are the eggs frozen?

The egg is the largest cell in the human body and contains a high amount of water. When the egg is frozen, the ice crystals that form can destroy the integrity of the cell. To prevent this, the egg must be dehydrated prior to freezing. This is done using cryoprotectants which replace most of the water within the cell and inhibit the formation of ice crystals. Then these eggs are stored as long as required in the IVF Lab.

How are these eggs used later to make the embryo?

When the woman desires to have a baby, she is put on medicines to prepare her uterus and her body to receive the embryo. Then the eggs are thawed and a special fertilization procedure is performed by an embryologist whereby sperm is injected directly into the egg with a needle. This injection technique is called ICSI (Intracytoplasmic Sperm Injection) and is also used in IVF.

Are the babies formed from frozen eggs normal?

Two recent studies showed that the rate of birth defects and chromosomal defects when using cryopreserved oocytes is consistent with that of natural conception.


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