What causes endometriosis?

What causes endometriosis?

The cause of endometriosis is unknown. Some experts believe that pieces of endometrium travel back through the fallopian tubes and pass out into the pelvic cavity (space inside the pelvis that holds the reproductive organs). Tiny pieces of tissue may lodge on surfaces of the reproductive organs. During menstruation, the tissue bleeds, just like the endometrium inside the uterus. Surrounding tissue may become inflamed. Over time, scar tissue and cysts can form.