Endometriosis is a puzzling disease affecting women in their reproductive years. The name comes from the word "endometrium," which is the tissue that lines the inside of the uterus and builds up and sheds each month in the menstrual cycle. In endometriosis, tissue I like the endometrium is found outside the uterus, in other areas of the body. In these locations outside the uterus, the endometrial tissue develops into what are called "nodules," "tumors," "lesions," "implants," or "growths." These growths can cause pain, infertility, and other problems.

The most common locations of endometrial growths are in the abdomen_involving the ligaments supporting the uterus, the area between the vagina and the rectum, the outer surface of the uterus, and the lining of the pelvic cavity. Sometimes the growths are also found in abdominal surgery scars, on the intestines or in the rectum, on the bladder, vagina, cervix, and vulva (external genitals).

Endometrial growths have also been found outside the abdomen, in the lung, arm, thigh, and other locations, but these are uncommon. Endometrial growths are generally not malignant or cancerous_they are a normal type of tissue outside the normal location. (However, in recent decades there has been an increased frequency of malignancy occurring or being recognized in conjunction with endometriosis.) Like the lining of the uterus, endometrial growths usually respond to the hormones of the menstrual cycle. They build up tissue each month, break down, and cause bleeding.

However, unlike the lining of the uterus, endometrial tissue outside the uterus has no way of leaving the body. The result is internal bleeding, degeneration of the blood and tissue shed from the growths, inflammation of the surrounding areas, and formation of scar tissue. Other complications, depending on the location of the growths, can be rupture of growths (which can spread endometriosis to new areas), the formation of adhesions, intestinal bleeding or obstruction (if the growths are in or near the intestines), interference with bladder function (if the growths are on or in the bladder), and other problems. Symptoms seem to worsen with time, though cycles of remission and reoccurrence are the pattern in some cases.

The most common symptoms of endometriosis are pain before and during periods (usually worse than "normal" menstrual cramps), during or after sexual activity, infertility, and heavy or irregular bleeding. Other symptoms may include fatigue; painful bowel movements with periods; lower back pain with periods; diarrhea and/or constipation and other intestinal upset with periods Some women with endometriosis have no symptoms. Infertility affects about 30-40% of women with endometriosis and is a common result with progression of the disease.

The amount of pain is not necessarily related to the extent or size of growths. Tiny growths(called"petechial")have been found to be more active in producing prostaglandins, which may explain the significant symptoms that often seem to occur with small implants. Prostaglandins are substances produced throughout the body, involved in numerous functions, and thought to cause many of the symptoms of endometriosis.