Egg retrieval is a procedure central to fertility treatments like in vitro fertilization (IVF) and egg freezing. It involves collecting mature eggs from the ovaries. Its purpose is to obtain viable eggs for fertilization or cryopreservation.
Ovarian Stimulation and Monitoring
Ovarian stimulation prepares the body to produce multiple mature eggs before retrieval. Fertility medications, typically daily hormone injections, encourage the ovaries to develop more than the single egg usually produced in a natural cycle. These medications often include follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which stimulate the growth of egg-containing follicles.
During this stimulation period, which typically lasts 7 to 12 days, regular monitoring tracks the ovaries’ response. This involves transvaginal ultrasounds to measure follicle size and count. Blood tests assess hormone levels, particularly estrogen, which rises as follicles mature.
This continuous monitoring provides data, allowing the fertility team to adjust medication dosages. By observing follicle growth and correlating it with rising estrogen levels, specialists gather information to determine the optimal time for retrieval.
Pinpointing the Right Moment
Determining the exact timing for egg retrieval is a precise and crucial step in an IVF cycle. Data from follicular monitoring, including follicle size and hormone levels, guides this decision. Specialists aim for most follicles to reach a mature size, typically 18 mm to 22 mm, before triggering final maturation.
Once follicles are ready, a “trigger shot” is administered. This injection contains hormones, most commonly human chorionic gonadotropin (hCG) or a GnRH agonist, which mimic the body’s natural luteinizing hormone (LH) surge. The trigger shot induces the final maturation of eggs within the follicles, preparing them for release.
The timing of this shot is critical, as egg retrieval must occur just before natural ovulation. Retrieval is typically scheduled 34 to 36 hours after the trigger shot. This narrow timeframe is essential for maximizing the number of mature, viable eggs collected. Retrieving them too early might result in immature eggs, while waiting too long could mean the eggs are prematurely released from the follicles.
The Retrieval Process
The egg retrieval procedure is performed, typically in an outpatient setting. It is usually conducted under sedation or light anesthesia, ensuring the patient experiences no discomfort.
During the procedure, a physician uses transvaginal ultrasound guidance to visualize the ovaries and mature follicles. A thin, hollow needle is inserted through the vaginal wall and into each follicle. Gentle suction aspirates the fluid, which contains the eggs.
The retrieved fluid is passed to an embryology laboratory. Embryologists examine the fluid under a microscope to identify and isolate the eggs. The entire retrieval process usually takes 10 to 30 minutes, depending on the number of follicles aspirated.
What Happens After Retrieval
Following the egg retrieval procedure, patients are moved to a recovery area for monitoring as the sedation wears off. It is common to experience mild side effects such as cramping, bloating, and light vaginal spotting, which are generally manageable with over-the-counter pain relievers. Most individuals can resume normal activities the day after the procedure, although rest is recommended for the remainder of the retrieval day.
The next steps depend on the purpose of the egg retrieval. If the eggs are intended for immediate IVF, they are transferred to an incubator and then combined with sperm for fertilization in the laboratory, either through conventional insemination or intracytoplasmic sperm injection (ICSI). For individuals undergoing egg freezing, the mature eggs are cryopreserved using a rapid freezing technique called vitrification, allowing them to be stored for future use.