<prompt> False about gallstone ileus90 patients give history of biliary diseaseCauses 1 of all SBO ; around 25 cases in 70 yearsTumbling obstructionFistula is mostly formed between duodenum and gallbladder  <response>: Option B: Riglers triad - Classic plain abdominal film of triad of small bowel obstruction, pneumobilia ectopic gallstone Option C: pain may be episodic and recurrent as the impacted stone temporarily obstructs the bowel lumen and then dislodges and moves distally, known as tumbling obstruction Option D: most common site of biliary enteric fistula is gallbladder and duodenum So opting for option A. Ref: Sabiston 20th edition Pgno : 1506-1507 