Oocyte freezing, also known as oocyte cryopreservation or egg freezing, is a fertility preservation technique that involves the extraction, freezing, and storage of a woman’s unfertilized eggs (oocytes) for future use in assisted reproductive technologies (ART), such as in vitro fertilization (IVF).
Here’s an overview of the oocyte freezing process:
Before egg retrieval, the woman undergoes ovarian stimulation with hormonal medications to encourage the development of multiple mature eggs. This typically involves daily injections over a period of approximately 8-14 days. During this time, the woman is monitored with ultrasound scans and blood tests to assess ovarian response and adjust medication dosages as needed.
Once the eggs are mature, a minor surgical procedure called egg retrieval is performed under sedation or anesthesia. A thin needle is guided through the vaginal wall to aspirate the eggs from the ovarian follicles. The procedure usually takes about 15-30 minutes and is performed in an outpatient setting.
After retrieval, the unfertilized eggs are immediately vitrified (rapidly frozen) using a specialized solution to protect them from damage during the freezing process. Vitrification involves plunging the eggs into liquid nitrogen at extremely low temperatures, which solidifies them without the formation of ice crystals.
Once vitrified, the eggs are stored in cryogenic storage tanks filled with liquid nitrogen, where they can be preserved for many years without significant deterioration.
When the woman is ready to use the preserved eggs for fertility treatment, the vitrified eggs are thawed using a controlled process. Thawed eggs are then fertilized with sperm, either from the woman’s partner or a sperm donor, through IVF. The resulting embryos are cultured in the laboratory for several days to allow for development.
Once embryos have developed, one or more embryos are selected for transfer to the woman’s uterus. This typically occurs 3-5 days after fertilization, depending on embryo quality and developmental stage. The embryos are transferred using a thin catheter inserted through the cervix into the uterus.
Oocyte freezing offers women the opportunity to preserve their fertility and have biological children in the future, even if they are not ready to start a family at the time of egg retrieval. It’s important for women considering oocyte freezing to consult with a fertility specialist to discuss their options, understand the process, and make informed decisions about their reproductive health.