Endometriosis is a condition in which the tissue that normally lines the uterus (endometrium) grows in other areas of the body, causing pain, irregular bleeding, and possible infertility.
The tissue growth (implant) typically occurs in the pelvic area, outside of the uterus, on the ovaries, bowel, rectum, bladder, and the delicate lining of the pelvis. However, the implants can occur in other areas of the body, too.