Endometriosis occurs when patches of endometrial tissue, which is normally found only in the uterine lining (endometrium), grow outside the uterus. Misplaced tissue flows backward through the fallopian tubes toward the ovaries and into the abdominal cavity, rather than out of the body through the vagina with the menstrual flow. Endometriosis is diagnosed by direct viewing during surgery (laparoscopy). Hormonal, surgical treatments and assisted reproductive methods may be helpful for the treatment of infertility associated with endometriosis.