Endometriosis is most often found in the ovaries, on the fallopian tubes, and the ligaments supporting the uterus, in the internal area between the vagina and rectum, on the outer surface of the uterus, and on the lining of the pelvic cavity. Very rarely, endometrial growths have been found outside the abdomen, in the thigh, arm, or lung. Physicians may use stages to describe the severity of endometriosis. Endometrial implants that are small and not widespread are considered minimal or mild endometriosis. Moderate endometriosis means that larger implants or more extensive scar tissue is present.
Severe endometriosis is used to describe large implants and extensive scar tissue.
Most commonly, the symptoms of endometriosis start years after menstrual periods begin. Over the years, the symptoms tend to gradually increase as the endometriosis areas increase in size. After menopause, the abnormal implants shrink away and the symptoms subside. Infertility occurs in about 30 to 40 percent of women with endometriosis. Rarely, the irritation caused by endometrial implants may progress into infection or abscesses causing pain independent of the menstrual cycle.