We present a very unusual case of diarrhoea in a 77-year-old man. He had a previously complicated surgical history, with a loop ileostomy and a colonic mucous fistula. He developed a sudden onset of diarrhoea from his mucous fistula. A contrast enema suggested a cholecystocolonic fistula and subsequent computed tomography demonstrated a common bile duct stone caused a degree of obstruction. The patient was treated successfully by endoscopic retrograde cholangiopancreatography and stone extraction. This case demonstrated the role that contrast enema may still play in unusual cases of diarrhoea.