Endometriosis is a very common benign disease that usually afflicts women over 35. Women who have deferred childbearing may be present with endometriosis. The cells that form the inner lining of the uterus besides being shed by menstruation may enter the abdominal cavity by a mechanism that is called retrograde menstruation. In certain women the defense machenism of the peritoneal cavity are unable to cope with the influx and the endometrial cells attach to the peritoneum and start to grow.

The most common sites of growth are the peritoneum (inner lining of the abdomen) and the ovaries. Located on the ovaries these cells eventually form cysts called endometriomas. Endometriosis may be located more deeply under the peritoneum. The etiology of deep endometriosis is different from peritoneal and ovarian disease.

The symptoms of the disease are pain, ovarian cysts, and infertility. Pain is usually more severe during menstruation. If endometriosis is deep the patient may complain of centralized dull pain that radiates to the lower back and the rectum. Pain during intercourse may be severe further contributing to infertility by making intercourse difficult.

The diagnosis of endometriosis is by laparoscopy unless the woman has a typical endometrioma on ultrasound. The diagnosis is deep endometriosis is more difficult and may require assistance from magnetic resonance imaging (MRI). Once endometriosis diagnosed by laparoscopy it should be treated surgically during the same session as this has been shown to improve pregnancy rates. It is debatable whether laparoscopy should be undertaken in asymptomatic women suspected to have endometriosis but with a normal pelvic examination. Furthermore, it is unknown in women with endometriomas whether surgical removal is better than referring the patient directly to IVF. Surgical removal of the endometrioma may adversely affect the ovarian reserve on that side and thus further contributing to infertility.

Medical treatment of endometriosis has not been shown to benefit the woman with infertility and should be reserved only for women presenting with pelvic pain who decline surgery or in whom surgery is predicted to be technically challenging.