Assessment of the common bile duct before cholecystectomy: a direct comparison between ultrasonography and intravenous cholangiography.

Sixty-seven consecutive patients undergoing cholecystectomy for symptomatic gallstones were investigated by both ultrasonography (US) and intravenous cholangiography (IVC). This provided the opportunity to compare these methods for assessing the common bile duct (CBD) preoperatively for stones. The results were correlated with a subsequent definitive procedure that formed the diagnostic standard in each case. The CBD diameters of 8 (12%) patients with stones was significantly greater than those without stones (t = 10.96, P < 0.001). Sensitivities of US and IVC were 87.5% and 100% respectively, but there were three unsuccessful IVC investigations that had to be excluded from the calculations. Specificities and overall accuracy of both methods were greater than 95%. The positive and negative predictive value of each test was similar and no difference using McNemar's test was found between US and IVC for providing information relating to CBD stones. Performing both procedures as routine assessment of the CBD is thus unnecessary as US, in conjunction with clinical history and liver biochemistry profile, provide an adequate preoperative screen of the CBD.