Plain x-ray of the abdomen may be helpful if it reveals features of intestinal obstruction, shows calcified gallstone in the intestinal lumen or air in the biliary system. Pneumobilia is present in only one third of cases, as occlusion of the cystic duct or common bile duct results from inflammatory process within the gallbladder. The gas in the gallbladder fossa is not always recognized in plain abdominal radiography and recognition of gallstones in the intestinal lumen depends upon the density of calcium in the stone .

Ultrasound may provide a definitive diagnosis of gallstone ileus and obviate the need for further tests. The presence of gas in the gallbladder and biliary tree is striking and at times it is possible to trace a dilated loop of the small bowel to the obstructing calculus and identify the exact site of the obstruction. However, the gallstone may lie much deeper in the abdomen, below the reflective loops of bowel and as such cannot be identified by ultrasound. Gas in the gallbladder fossa is also not often recognized. Absence of pneumobilia and ‘nature’ of shadowing in the gallbladder fossa remains a problem for ultrasound diagnosis of gallstone ileus .

CT, on the other hand, can demonstrate features of gallstone ileus including cholecystoduodenal fistula and the intraluminal gallstone in the bowel, even when this is not heavily calcified. Our case demonstrates all the features of gallstone ileus on CT including cholecystoduodenal fistula, size and number of stones in the intestinal lumen and site of intestinal obstruction. . In conclusion, CT provides all of the specific findings of gallstone ileus that are incompletely and infrequently demonstrated by plain abdominal radiography or by ultrasound. Early use of CT in elderly people with clinical features of intestinal obstruction helps to identify gallstone ileus, which is associated with significant morbidity and mortality if left untreated