The Diameter of Common Bile Duct Does not Predict the Cause of Extrahepatic Cholestasis

Abstract

Extrahepatic cholestasis is usually caused by either a bile duct stone or a stricture. In early phase in primary care, when novel imaging studies such as magnetic resonance cholangiopancreatography or endoscopic retrograde cholangiopancreatography (ERCP) are seldom available, the differential diagnosis between benign and malignant causes is clinically challenging. The aim of the present study was to analyze the value of the degree of common bile duct dilatation in differential diagnosis of extrahepatic cholestasis. In all, 212 consecutive patients in whom a bile duct stricture (n=103) or a stone (n=109) had been found in ERCP were included in the study population. The maximum diameter of the common bile duct was measured from ERCP images. Plasma bilirubin concentration was measured before ERCP. The median (range) values for the common bile duct diameter for the patients with a stricture and those with a stone were 16 (5 to 33 mm) and 15 mm (6 to 29 mm), respectively (P=0.0038). In receiver operating characteristic analysis, the difference was barely significant when compared with random value (P=0.0399). Area under curve for bile duct diameter was 0.615. In conclusion, the degree of bile duct dilatation does not aid in differential diagnosis between benign and malignant causes of extrahepatic cholestasis.