A condition in which tissue similar to the uterine lining (the endometrium) implants and grows outside the uterus. Endometrial growths are often found on the ovaries, fallopian tubes, peritoneum, bowel, bladder, and/or vagina, but may also grow in other areas of the body. Each month the endometrial growths respond to the hormonal cycle, resulting in inflammation, lesions, adhesions, and cysts. Endometriosis can cause a variety of symptoms, including menstrual pain, painful intercourse, pelvic pain, bowel changes, heavy menstrual bleeding, bloating, fatigue, and infertility.