<prompt> Most common site of Gallstone ileus:Caecum2nd pa of duodenumTerminal ileumStomach  <response>: Gallstone ileus is an unusual complication of chronic cholecystitis due to impaction of gallstone in ileum after passing through a biliary-enteric fistula. Impacted gallstone usually in the terminal ileum at ileocecal valve Riglers Triad: Pneumobilia Small bowel obstruction Gallstone at terminal ileum 