Colonic gallstone ileus.

We present a rare case of colonic gallstone obstruction in a patient with cholecystocolic fistula. Ultrasound was able to detect the Rigler triad whereas plain film initially only showed ileus. Contrast enema and ERCP failed to show a biliary-enteric fistula. Only the combination of colonoscopy and contrast fistulography evidenced the cholecystocolic connection. The difficulties in establishing the correct radiologic diagnosis of gallstone ileus and in visualizing the biliary-enteric fistula are discussed.