What is Endometriosis
Endometriosis is a painful, chronic disease that affects 5 1/2 million women and girls in the USA and Canada, and millions more worldwide.
It occurs when tissue like that which lines the uterus (tissue called the endometrium) is found outside the uterus -- usually in the abdomen on the ovaries, fallopian tubes, and ligaments that support the uterus; the area between the vagina and rectum; the outer surface of the uterus; and the lining of the pelvic cavity. Other sites for these endometrial growths may include the bladder, bowel, vagina, cervix, vulva, and in abdominal surgical scars.

Less commonly they are found in the lung, arm, thigh, and other locations.
This misplaced tissue develops into growths or lesions which respond to the menstrual cycle in the same way that the tissue of the uterine lining does: each month the tissue builds up, breaks down, and sheds. Menstrual blood flows from the uterus and out of the body through the vagina, but the blood and tissue shed from endometrial growths has no way of leaving the body. This results in internal bleeding, breakdown of the blood and tissue from the lesions, and inflammation -- and can cause pain, infertility, scar tissue formation, adhesions, and bowel problems