Endometriosis

Whatever the cause of endometriosis, it is thought that faulty immune defenses play some role in its development. The immune system apparently fails to identify and destroy endometrial tissue growing outside of the uterus where it does not belong, and may even promote the growth and proliferation of this tissue. Research is being done to understand the relationship between the immune system and endometriosis.

In the United States, endometriosis affects an estimated 10% to 20% of women of childbearing age. The average person with endometriosis is diagnosed at age 27, although she may have had symptoms for two to five years before the diagnosis is confirmed.

In general, a woman probably has a higher-than-average risk of endometriosis if any of the following is true:

• She has a heavy menstrual flow.

• She has a short menstrual cycle (27 days or less).

• She has a close female relative (mother, sister, daughter) with endometriosis.

A woman's risk is probably lower than average if any of the following is true:

• She is slightly underweight.

• She exercises regularly.

• She has had multiple pregnancies.

• She has used oral contraceptives (birth control pills).

Symptoms

Many women with endometriosis do not have any symptoms. Those who have symptoms may experience any of the following:

• Severe menstrual discomfort, usually with heavy menstrual flow

• Periodic pain in the pelvis or abdomen, usually either just before or during menstruation

• Backache

• Pain during or immediately after sexual intercourse

• Vaginal spotting before menstruation begins

• Bowel symptoms, such as painful bowel movements, diarrhea, constipation or, rarely, blood in the stool

• Painful urination, or, rarely, blood in the urine

• Infertility or repeated miscarriages

In general, the severity of symptoms depends on the location of a woman's endometriosis rather than its size. A woman who has only a few small patches of misplaced endometrial tissue may have severe pelvic pain, while a woman with larger areas of endometriosis may feel no symptoms at all.