Definition: Endometriosis is characterized by the growth of endometrium-like tissue outside of the uterus. Deposits are most commonly distributed in the pelvis, ovaries, uterosacral ligaments, pouch of Douglas, rectum and sigmoid colon, bladder, and distal ureter. Extrapelvic deposits such as the bowel, diaphragm, umbilicus and pleural cavity are rare. It is hormone mediated and associated with menstruation. Hormone changes in the menstrual cycle induce bleeding, chronic inflammation and scar tissue.