Egg freezing, or oocyte cryopreservation, is a procedure in which the eggs (oocytes) of a woman are extracted, frozen, and stored as a technique to maintain in reproductive capacity in a woman of reproductive age. Unfertilized eggs obtained from ovaries are frozen and preserved for later use. Frozen egg is thawed, mixed with sperm in a lab and then implanted in a uterus (IVF). Over the past few years, oocyte cryopreservation has progressed dramatically, with increased overall performance of eggs surviving the freezing process.
Based on your needs and reproductive history, the doctor will help you understand how egg freezing functions, the possible risks and whether the fertility preservation approach is right for you.
If you’re not ready to get pregnant now but want to try to make sure you can get pregnant later, then egg freezing might be an option.
Egg freezing does not require sperm, as with fertilized egg freezing (embryo cryopreservation), since the eggs are not fertilized until they are frozen. However, just as with embryo freezing, you will need to use fertility drugs to help you ovulate so that multiple eggs will be developed for retrieval.
To try to conceive a child with sperm from a partner or a sperm donor, you can use frozen eggs. The embryo can also be implanted in another person’s uterus to carry the baby (gestational carrier).
You are likely to have some blood screening tests before starting the egg-freezing process, including:
There are multiple steps to egg freezing — ovarian stimulation, egg retrieval and freezing.
Instead of the single egg that typically develops monthly, you’ll take synthetic hormones to stimulate your ovaries to produce multiple eggs. Drugs that might be required include:
Your doctor will monitor you during treatment. To measure your response to ovarian-stimulation medications, you will have blood tests. As follicles develop, estrogen levels typically rise, and progesterone levels stay low until after ovulation.
In order to track the development of fluid-filled sacs where eggs mature- follow-up visits will often include vaginal ultrasound- a technique that uses sound waves to produce a picture of the inside of your ovaries (follicles).
An injection of human chorionic gonadotropin (Pregnyl, Ovidrel) or another drug may help the eggs mature when the follicles are ready for egg retrieval, normally after 10 to 14 days.
Egg retrieval is performed under sedation, usually in your doctor's office or a clinic. Transvaginal ultrasound aspiration is a common approach, during which an ultrasound probe is inserted into your vagina to locate the follicles.
A needle is then directed through the vagina and into a follicle. To extract the egg from the follicle, a suction device which is attached to the needle is used. Multiple eggs may be removed and studies indicate that the more eggs collected— up to 15 per cycle — the higher the chances of birth.
You may have cramps after egg retrieval. For weeks, feelings of fullness or discomfort can persist because your ovaries stay swollen.
Your unfertilized eggs are cooled to sub-zero temperature shortly after they are harvested to protect them for future use. The development of an unfertilized egg makes it a little harder to freeze and lead to a healthy pregnancy than does the development of a fertilized egg (embryo).
The method most widely used for egg freezing is called vitrification. With rapid cooling, high concentrations of substances that help prevent the formation of ice crystals during the freezing process (cryoprotectants) are used.
After the procedure, usually, within a week of egg retrieval, you can resume daily activities. To prevent an accidental pregnancy, avoid unprotected intercourse.
Egg freezing carries various risks, including:
If you use your frozen eggs to have a child, the chance of miscarriage will be mainly based on your age at the time your eggs were frozen. Older women, having older eggs, have higher miscarriage rates.