<prompt> Which of the following is not a diagnostic feature of gallstone ileus on a plain abdominal radiograph?Ectopic calcified gallstoneStone 2.5 cm size in the intestineSigns of small intestinal obstructionGas in the biliary tree  <response>: Characteristic feature of gallstone ileus is Riglers triad :Incomplete or complete small bowel obstruction; Gas in biliary tree; Ectopic gallstone. 