Endometriosis. Laparoscopic view of endometriotic spots (right) in the abdominal cavity, a telltale sign of endometriosis. This condition occurs when uterine tissue (the endometrium) is found outside the uterus in other areas of the body. The endometrium is normally shed each month during menstruation but endometrial tissue found outside the uterus, such as in the abdominal cavity, cannot leave the body. This causes painful internal bleeding, tissue shedding, inflammation of the surrounding areas, and scar tissue that interferes with the functioning of abdominal organs. There is no cure for this condition but it can be controlled by surgical treatments.