According to the Eunice Kennedy Shriver National Institute of Child Health and Human Development, endometriosis occurs when the tissue that normally lines the uterus grows outside the uterus. Affecting roughly five million women in the United States alone, endometriosis may appear in patches, most of which are found in the pelvic cavity. These patches may be found on or under the ovaries, on the fallopian tubes, behind the uterus, on the tissues that hold the uterus in place or on the bowels or bladder. Recent research into the relationship between the pain resulting from endometriosis and the location of endometriosis patches found that the location of the patches is not related to the severity of the pain or even the location of the pain. That pain can be considerable, and women with endometriosis may experience various kinds of pain, including very painful menstrual cramps and chronic pain in their lower backs and pelvic regions. Some women with endometriosis experience pain during or after sex, and others have intestinal pain or pain when urinating or having a bowel movement. An inability to get pregnant and digestive problems, including diarrhea, constipation, bloating or nausea, especially during menstrual periods, may also occur. More information about endometriosis is available at www.womenshealth.gov.