<prompt> Toxic megacolon is most commonly associated with:Ulcerative colitisCrohns diseaseWhipples diseaseReiters disease  <response>: Ans. A. Ulcerative colitisComplications of Ulcerative colitis:a. Massive hemorrhage.b. Toxic mega colon with perforation.c. Colonic epithelial dysplasia and carcinoma. The risk of neoplasia increased with duration and extend of the disease. 