IVF Ovarian Stimulation
- During in vitro fertilization (IVF), a woman's body is induced to produce multiple follicles and eggs, as opposed to the one follicle and one egg which are developed and released during a natural menstrual cycle. In order to stimulate the ovaries to make more eggs, special ovarian stimulation medication protocols are used.
- The eggs are then removed from a woman's body and fertilized in the laboratory with her partner's sperm.
- After culturing the eggs for a few days, the best-looking embryos are selected and transferred back into the woman's body.
Egg Production via Ovarian Stimulation
In IVF the ovaries are stimulated to produce a high number of follicles and eggs. In order to do so, fertility drugs (ovulation stimulating medications) are used. To maximize the success of IVF treatments, ideally 8-15 quality eggs will be available when it is time to retrieve the eggs.
The common IVF fertility drugs contain follicle stimulating hormone (FSH) or are drugs that mimic the action of the body's natural luteinizing hormone (LH). Specifically, to develop multiple follicles, FSH products are used, such as Gonal-F, Follistim, Menopur, and Bravelle. To suppress the LH surge and delay ovulation until the follicles are mature, either a GnRH-agonist (i.e. Lupron) or a GnRH-anagonist (i.e. Cetrotide) is used. Finally, to trigger the final LH surge and ovulation, hCG or human chorionic gonadotropin is administered.
The woman is stimulated with the injectable FSH medications for about 8-12 days until multiple mature size follicles have developed.
While a sufficient number of eggs must be produced in order for IVF to be successful, one of the risks involved in using drugs to stimulate the ovaries is over-stimulating the ovaries, which is not only uncomfortable for the woman but can give rise to a condition called ovarian hyperstimulation syndrome (OHSS). In OHSS the ovaries are over-stimulated and become swollen and filled with fluid. While usually mild, in severe cases the bloated ovaries can rupture and leak, causing great pain for the woman and potential serious medical consequences.
Role of Infertility Specialist
Therefore fertility specialists must carefully select an appropriate medication regimen wherein the ovaries are not under-stimulated or over-stimulated. Some doctors prescribe albumin, a protein solution, to lower the risk of developing OHSS. Periodic pelvic ultrasounds examining the ovaries should be conducted regularly and estrogen levels should be carefully monitored. Estrogen blood levels are in important measure since estrogen levels at baseline are usually under 60 pg/ml and increase as multiple follicles develop. The ideal time for the hCG injection - the inducer of the final surge to trigger egg release - is when estrogen levels and follicle measurements appear optimal for a successful IVF outcome. Following hCG injection, egg retrieval is planned for 34-35 hours later, or shortly before ovulation.
Ovulation Stimulation Candidates and Success Rates
Research indicates low IVF success rates with stimulation of less than 3 mature follicles. Ideally, four to five mature follicles should be available for IVF.
Some women are thought to be poor candidates for ovarian stimulation. These include:
•- women older than 37 years of age
•- women with reduced ovarian reserve
•- women with elevated FSH levels (signaling the onset of men0pause)
•- women with low antral follicle counts