<prompt> Which does not contribute to enterobiliary fistulaGastric ulcerDuodenal ulcerCarcinoma gallbladderGallstones  <response>: Internal biliary fistula Cholecystoduodenal fistula72-80 are MC biliary enteric fistulas followed by cholecysticolic fistula 8-12. Etiology Calculous biliary tract disease 90. Duodenal ulcer6 Neoplasm, trauma, Parasitic infestation and congenital anomalies 4 Ref : Sabiston 20th edition Pgno :1507 