Interobserver agreement in ultrasound examination of the biliary tract

To prospectively evaluate the interobserver agreement in US examination of the gallbladder and the biliary tract performed by an experienced and a novice radiologist.

Fifty consecutive patients underwent US examination because of clinically suspected gallstones. The examination was performed by a consultant and a trainee radiologist on the same day. The following outcome measures were registered: presence of gallstones, filling of the gallbladder, thickness of the gallbladder wall, splitting of the gallbladder wall, fluid around the gallbladder, diameter of the common bile duct (CBD), and presence of CBD stones.

None of the radiologists observed CBD stones or fluid around the gallbladder. The CBD was clearly distinguished by both observers in all patients. There was good agreement in the conclusions of the two radiologists regarding the presence of gallbladder stones and substantial agreement regarding the filling of the gallbladder and splitting of the gallbladder wall. Significant difference existed in the measurements by the two radiologists regarding the thickness of the gallbladder wall and the diameter of the CBD.

The novice radiologist's expertise in the primary diagnosis of uncomplicated gallstone disease was as good as the one provided by the experienced colleague. The significant interobserver difference in the measurements of the thickness of the gallbladder wall and the CBD diameter might indicate that assessment of these parameters requires extensive practise and the opinion of an experienced colleague must be sought in cases where complications are suspected.