Two to 10 percent of premenopausal women are affected by endometriosis, a non-cancerous condition in which pieces of the endometrium (uterine lining) grow outside the uterus and adhere to other pelvic structures, most commonly the ovaries, bowel, fallopian tubes or bladder. The most common symptoms are painful menstrual periods and/or pelvic pain. The type and intensity of symptoms range from completely disabling to mild. Sometimes, there aren't any symptoms. Learn more about endometriosis by following the links below: