Most common site of gall stone impaction is

Gall stone ileus It is an acute intestinal obstruction, often seen in elderly and is due to Blockage be a bolus or mass of gallstones which commonly enter the intestines through cholecystoduodenal fistula (75%) or rarely through cholecystointestinal or gastric fistula MC site : Between gallbladder and duodenum 2nd MC site : Between gallbladder and transverse colon Obstruction is seen in Distal ileum or proximal to ileocaecal junction Ref: SRB's Manual of Surgery 5th edition Pgno : 648