Endometriosis is a condition where tissue similar to the lining of the uterus grows outside the uterus, most commonly on the ovaries, fallopian tubes, and tissues lining the pelvis. This displaced tissue responds to the menstrual cycle and breaks down and bleeds each month, but with no way to exit the body. Symptoms include painful periods, pain with intercourse, pain with bowel movements or urination, heavy bleeding, and infertility. Treatment options include pain medication, hormonal therapy, surgery, and lifestyle changes.