When a woman has endometriosis, the tissue that lines her uterus, called the endometrium, grows outside of the uterus. No one is sure why this happens. When this tissue grows outside of the uterus, it is mostly found in the pelvic cavity, usually in one or more of these places: on or under the ovaries, behind the uterus, on the tissues that hold the uterus in place, or on the bowels or bladder.
General symptoms of endometriosis can include (but are not limited to):
extremely painful (or disabling) menstrual cramps; pain may get worse over time
chronic pelvic pain (includes lower back pain and pelvic pain)
pain during or after sex
intestinal pain
painful bowel movements or painful urination during menstrual periods
heavy menstrual periods
premenstrual spotting or bleeding between periods
infertility (not being able to get pregnant)