Endometriosis is a condition in which the endometrium, tissue that normally lines the uterus, grows in other areas of the body, causing pain, irregular bleeding, and frequently infertility.
The tissue growth typically occurs in the pelvic area, outside of the uterus, on the ovaries, bowel, rectum, bladder, and the delicate lining of the pelvis, but it can occur in other areas of the body as well.