What Is Egg Freezing?
Egg freezing, also known as oocyte freezing, has been around for years, but generally has been less than successful and only available as an experimental technique of fertility preservation.
While embryo freezing –- which is the freezing of a fertilized egg –- works well, freezing unfertilized eggs is trickier. If a young or single cancer patient wants to preserve her fertility, freezing fertilized embryos would only be an option if donor sperm is used to fertilize the eggs.
That's why researchers have been experimenting with freezing unfertilized eggs, to provide options to young or single cancer patients. Some female cancer patients risk losing their fertility because certain kinds of chemotherapy treatments, and certain types of radiation treatments, can bring on premature menopause, rendering them sterile. Not all cancer treatments lead to infertility, but many do.
There is also interest in the subject as a method of extending fertility in healthy women, possibly taking away age-related barriers to childbearing. Eggs frozen from your younger years, theoretically, could be used years later during IVF treatment, if age-related infertility strikes before you're ready to have kids.
What Is Oocyte Vitrification?
Until recently, the only method for freezing oocytes (or unfertilized eggs) was a slow-freezing method. Unlike sperm, which has been successfully frozen and used for years, eggs contain a great deal of water, which makes freezing more difficult. When the eggs are frozen, ice crystals can form within the egg. These ice crystals can destroy the cell's structure.
To help minimize the amount of ice crystals, scientists would remove some of the water as the egg was slowly frozen. But it's impossible to remove all the water, and they couldn't prevent the formation of some ice crystals. The fertilization and pregnancy rates for these slow-frozen eggs, once thawed, is low.
Vitrification is a specialized freezing technique, which freezes the egg so quickly, ice crystals don't have time to form.
When Is Egg Freezing With Vitrification Used?
Embryo freezing is still the preferred technique for fertility preservative, but this new technique is being used for young or single cancer patients, who don't want to use a sperm donor. Egg vitrification is still considered to be experimental.
In research labs, vitrification is also being tried out for ovarian tissue preservation. Ovarian tissue preservation, also known as ovarian cryopreservation, is another experimental technique being used to preserve fertility in female cancer patients. It involves removing one ovary or part of an ovary, freezing it, and later, implanting the ovary in the woman's body after cancer treatment is completed.
Vitrification of eggs is also being used to help preserve fertility in young women who want to delay motherhood, but don't want to worry about age-related infertility. As women get older, the risk that they'll have trouble conceiving rises. Some fertility clinics are marketing vitrification to women who want to wait for motherhood, or don't have partners yet and are worried about their ticking biological clocks.
Sperm can be preserved by freezing and used for treatment at a later time. There are various reasons why you may feel you need to freeze your sperm, for instance:
- If you are about to undergo treatment such as chemotherapy which may result in infertility.
If you are planning to have a vasectomy.