What is Endometriosis? With endometriosis, cells which somewhat resemble the endometrium (the lining of the uterus ) are found outside the uterus where they don't belong. It is a benign (noncancerous) condition. According to the American College of Obstetricians and Gynecologists (ACOG), endometriosis is a common condition affecting 10 to 15 percent of reproductive-age women. It occasionally causes symptoms even after natural or surgical menopause. Read More |  |