Examination reveals marked tenderness in the RUQ without a palpable mass.
He is not jaundiced and there are no stigmata of chronic liver disease. An abdominal ultrasound suggests dilitation of the extrahepatic ducts to 17mm. The gallbladder wall is thickened and contains some sludge but no stones. Liver function tests are abnormal. His past history includes alcohol abuse, smoking, hypertension and diabetes.