Egg harvesting, formally called oocyte retrieval, is a short outpatient procedure that takes about 15 to 30 minutes. But the full process starts roughly two weeks earlier with hormone injections that coax your ovaries into producing multiple mature eggs at once. Here’s what each phase involves, from the first injection to recovery.
Ovarian Stimulation: The Two-Week Buildup
In a natural cycle, your ovaries release just one egg per month. For retrieval, fertility doctors use injectable hormones to stimulate multiple follicles (the tiny fluid-filled sacs that each contain an egg) to grow simultaneously. These injections typically contain follicle-stimulating hormone, the same hormone your body produces naturally, just at higher doses. Most protocols call for daily self-injections at 150 to 225 international units for about 10 to 14 days.
Alongside the stimulating hormones, you’ll also take a second medication that prevents your body from releasing the eggs too early. Without it, you could ovulate before the retrieval, and those eggs would be lost. The specific combination of drugs varies by protocol. Some start with a suppressing medication before stimulation begins, while others add it partway through, usually around day six or when follicles reach about 14 millimeters in size.
There’s also a “minimal stimulation” approach that uses lower doses and oral medications, resulting in far fewer injections. One comparison found that minimal protocols use roughly one-fifth the amount of injectable hormones compared to standard protocols. This approach yields fewer eggs but can be appropriate for certain patients, particularly those at higher risk of overstimulation.
Monitoring Visits During Stimulation
Throughout the stimulation phase, you’ll visit the clinic several times for transvaginal ultrasounds and blood draws. The ultrasound lets your doctor count developing follicles and measure their size. Blood tests track estrogen levels, which rise as follicles grow and help gauge how strongly your ovaries are responding. These visits allow your doctor to adjust medication doses and watch for signs that stimulation is progressing too aggressively. Most people visit the clinic every two to three days during this window, with visits becoming more frequent toward the end.
The Trigger Shot
When enough follicles reach 16 to 18 millimeters, you’ll receive a precisely timed “trigger shot.” This injection mimics the natural hormone surge that causes eggs to complete their final stage of maturation inside the follicle. The most common trigger is human chorionic gonadotropin (hCG), though some protocols use a different hormone or a combination of both.
Timing is critical. The retrieval is scheduled exactly 36 to 37 hours after the trigger shot. Too early and the eggs won’t be mature enough. Too late and the body may release them on its own. Your clinic will give you a specific time, sometimes in the middle of the night, to administer this injection.
The Retrieval Procedure
On retrieval day, the procedure itself is straightforward. An ultrasound probe is inserted vaginally to visualize the follicles on each ovary. A thin needle is then guided through the vaginal wall and into each follicle. A gentle suction device connected to the needle draws out the follicular fluid, which contains the egg. The doctor moves from follicle to follicle, draining each one. The whole process typically takes 15 to 30 minutes depending on how many follicles need to be aspirated.
You won’t feel this happening. In the United States, about 95% of fertility programs use conscious sedation, meaning you’ll receive intravenous medication that keeps you in a twilight state: breathing on your own but not aware of the procedure. In the UK, sedation is also the most common choice, used in roughly 84% of centers. General anesthesia (being fully unconscious) and regional anesthesia (like a spinal block) are less common alternatives.
What Happens in the Lab
As each follicle is drained, the fluid goes directly to an embryology lab, sometimes in an adjacent room or even inside the operating room itself. An embryologist examines the fluid under a microscope to locate and identify each egg, which is surrounded by a cluster of sticky cells called the cumulus. The eggs are carefully transferred to culture dishes, the surrounding cells are trimmed, and the eggs are placed in an incubator that mimics body temperature and conditions. All follicular fluid is kept at 36 to 38°C throughout this process to protect egg viability.
Not every follicle yields a usable egg. Some follicles may be empty, and some eggs may not be mature enough. That’s normal.
How Many Eggs to Expect
Age is the single biggest factor in how many eggs a retrieval produces. A study of over 3,400 cycles found these averages:
- Under 30: about 18 to 19 eggs per cycle
- 30 to 35: about 15 eggs
- 36 to 37: about 13 eggs
- 38 to 39: about 10 to 11 eggs
- 40 to 44: about 8 eggs
- 45 and older: about 4 to 5 eggs
These are averages with wide ranges. Someone under 30 might get anywhere from 8 to 29 eggs, while someone over 40 might get 1 to 15. More eggs doesn’t always mean better outcomes, either. The best live birth rates tend to come from retrievals that yield 11 to 15 eggs. For women between 35 and 39, a more modest 5 to 9 eggs is associated with the best pregnancy rates.
Recovery After Retrieval
You’ll spend about 30 minutes to an hour in a recovery area as the sedation wears off. Someone will need to drive you home. Most people take only the retrieval day off from work and resume light activities within a day or two.
The most common aftereffects are bloating, mild cramping in the lower abdomen, and fatigue. Your ovaries are still enlarged from stimulation, which accounts for much of the discomfort. Light vaginal spotting is normal for a day or two since the needle passed through the vaginal wall. Some nausea or dizziness from the anesthesia typically fades within three to five days.
You should avoid strenuous exercise and heavy lifting for at least a week. Pelvic twisting motions (like certain yoga poses or intense core work) should wait until bloating subsides and your ovaries return to normal size, because swollen ovaries are more vulnerable to twisting on their stalk, a painful condition called ovarian torsion. Most people feel fully back to normal by the end of their next period, which usually arrives 7 to 10 days after retrieval and tends to be heavier than usual.
Risks and Complications
The most well-known risk is ovarian hyperstimulation syndrome (OHSS), which affects 3% to 6% of women undergoing IVF. In most cases it’s mild, causing bloating, minor abdominal pain, and some weight gain that resolves on its own. OHSS typically develops a few days after retrieval, not during the procedure itself.
In rare cases, OHSS becomes serious. Warning signs include rapid weight gain (more than 2 pounds per day), severe abdominal pain or swelling, decreased urination, shortness of breath, and persistent vomiting. These symptoms need prompt medical attention. Other uncommon risks of the retrieval itself include infection and bleeding from the needle puncture site, though both are rare with modern ultrasound-guided technique.