Egg retrieval is one of a few steps completed during in vitro fertilization (IVF) or egg freezing. Once the ovarian follicles (containing eggs) have been identified and measured to ensure they are mature, the retrieval can take place. Using ultrasound guidance, a thin needle is inserted through the walls of the vagina to retrieve the eggs. The eggs are then removed through a suction device connected to the needle.
Egg retrieval is a procedure done in conjunction with in vitro fertilization (IVF) and egg freezing. During preparation for IVF, a patient takes hormone medications to prompt their ovaries to produce multiple mature eggs in one menstrual cycle, as opposed to the single egg usually ovulated. Then, their doctor is able to surgically remove those eggs during an egg retrieval procedure and bring them to a lab, where they can be frozen or fertilized with sperm to create embryos.
An egg retrieval is typically performed using a transvaginal ultrasound to identify the follicles, sacs of fluid in the ovaries that contain mature eggs. Once the follicles are identified, a thin needle is inserted through the vaginal wall to retrieve the eggs.
After retrieval, the mature eggs are then placed in a cultured medium and incubated. An analysis is then conducted to determine which eggs can be successfully combined with sperm to create embryos. Typically, it takes less than 24 hours to determine which eggs are mature enough for fertilization.
The eggs that successfully fertilize will be monitored as they develop over 5–6 days. Finally, one or two healthy embryos will be transferred into the patient’s uterus, where they will hopefully become a pregnancy.
IVF is designed for patients who have trouble conceiving, and experience infertility issues, including age-related infertility, endometriosis, ovulation disorders, and uterine fibroids, among other common causes. In addition, IVF and egg retrieval can assist couples in which the male partner suffers from male-factor infertility and reduced sperm production, including azoospermia, asthenospermia, and oligospermia.
Egg retrieval is also part of the process of egg freezing, in which patients can cryopreserve some eggs to potentially use later, when having a healthy pregnancy naturally may be more difficult. Egg freezing follows the same protocol as IVF, except that after egg retrieval, the eggs are frozen with liquid nitrogen and stored at -196ºC, instead of being fertilized.
Egg retrieval procedures were first developed in 1984 by Pierre Dellenbach and his colleagues in Strasbourg, France. Dellenbach used laparoscopy, an operation performed in the abdomen or pelvis using small incisions, to retrieve oocytes when IVF was first introduced. This method was later replaced by transvaginal oocyte retrieval. Today, the transvaginal ultrasound probe is the most commonly used technique for egg retrieval.