Overview of egg retrieval and freezing procedures
Please visit the video and image gallery to learn more about egg retrieval and egg freezing procedures.
Currently there are two basic approaches to egg retrieval and freezing.
- One approach involves obtaining eggs from the ovaries after they are stimulated to produce multiple eggs. These eggs are then frozen.
- Another method is to remove tissue from the ovaries. Ovarian tissue contains follicles, which in turn, contain eggs. The ovarian tissue is frozen and stored until use.
The methods used for egg freezing will vary depending on whether the eggs themselves or ovarian tissue is frozen.
Freezing eggs involves the injection of medications that will cause your ovaries to grow multiple ovarian follicles. Normally, each follicle contains an egg. During this process, you are monitored by ultrasound examinations and blood tests to determine when the follicles reach a mature size. Follicles typically require about eight to twelve days of injections to reach a mature size. Once the follicles appear mature, you will receive a hormone injection to induce final maturation of the eggs. The egg retrieval is scheduled for about 35 hours after this final injection.
The egg retrieval is performed by transvaginal ultrasound guided aspiration. After receiving a mild anesthesia, an ultrasound is performed using a vaginal ultrasound probe. The follicles are viewed using the ultrasound, and a small needle is passed through the vaginal wall and into each follicle. The fluid in the follicle is aspirated through the needle and into an attached tube and given to the laboratory staff, who retrieve the eggs and prepare them for freezing.
To freeze the eggs, they are placed in a special solution (called a cryoprotectant), which helps prevent damage to the eggs during the freezing and thawing processes. The eggs are then cooled at a carefully controlled rate, and once they reach an appropriate temperature they are stored in liquid nitrogen tanks.
For ovarian tissue freezing, tissue is obtained through a surgical procedure performed under a general anesthesia. The tissue is placed in a cryoprotective solution, cooled at an appropriate rate, and stored in liquid nitrogen.
While we have a great deal of experience in this technology, we want you to understand that egg freezing is still a very new procedure. As such, we do not know with any certainty if, for example, pregnancies resulting from frozen eggs are at higher risk of birth defects or chromosomal anomalies. We are currently gathering data from patients to explore these issues and how different patient-related factors impact egg freezing.
For example, a woman's age is likely to have a strong impact on the successful freezing and thawing of eggs because of some of the effects that aging has on her eggs. Because of such issues, and because the procedure is relatively new, some organizations, such as the American Society for Reproductive Medicine, recommend that egg freezing be considered investigational while more data is collected to measure the success of this procedure.