Endometriosis is a painful condition where the tissue that normally lines your uterus grows outside the uterine cavity. This abnormal growth results in chronic inflammation and complications such as adhesions, pelvic pain, and subfertility. Endometriotic implants most commonly involve pelvic structures such as the ovaries, fallopian tubes and peritoneum, but can also spread to the intestines, urinary tract and structures outside the pelvic cavity.