Endometriosis is a common condition affecting woman and may be present in 20-50% of women who have difficulty getting pregnant. Endometriosis usually occurs when the uterine lining (endometrium) “spills” out of the fallopian tubes during menstruation and begins to grow in a woman’s pelvis. Endometriosis is responsive to the hormone changes throughout a woman’s cycle and can cause pain in the days before and during menstruation. When endometriosis grows on or forms cysts in the ovaries it can reduce a woman’s egg (oocyte) supply and interfere with the release of eggs (ovulation) from the ovary. Endometriosis also causes scarring in the pelvis which can block or kink the fallopian tubes and prevent the egg (oocyte) from being fertilized. In moderate to severe cases of endometriosis, surgery may be required to remove cysts and scarring before pregnancy can be achieved. In milder cases, or in patients who do not want to get pregnant soon, endometriosis can often be managed with medications such as birth control pills or an injectable medicine called Lupron.