Many women with lower abdominal pain have endometriosis. Endometriosis is a condition in which the lining of the uterus (endometrium) is found outside of the uterus. The diagnosis of endometriosis is usually made at surgery. The treatment of endometriosis includes medical and surgical approaches alone or in combination. The hormone estrogen stimulates the growth of the endometrium and may also stimulate the growth of endometriosis. Medical therapies that act to decrease the level of estrogen can reduce the amount of endometriosis and pain. When therapies are discontinued, symptoms often return. In addition, medical treatment for endometriosis is expensive and is often associated with weak bones (osteoporosis) and hot flashes as a result of low levels of estrogen.