Comparison of intraoperative ultrasonography and cholangiography in detection of small common bile duct stones.

High-resolution intraoperative ultrasonography was compared with conventional radiographic imaging in the detection of small common bile duct (CBD) stones (less than 5 mm in diameter). Sixteen mongrel dogs had laparotomy and ligation of distal CBD; 1 week to 10 days later, 0-3 gallstones of varying sizes (2-5 mm) were introduced into the dilated CBD (6-16 mm). High-resolution intraoperative ultrasonography of the CBD and a conventional intraoperative cholangiogram were performed to detect the presence and number of stones. The results of these two tests were evaluated independently by two ultrasonographers and two surgeons. There were 21 true-positive and five false-negative readings by sonogram compared with 17 and 9, respectively, by cholangiogram. Sensitivity of the sonogram was 81% and 65.4% by cholangiogram. Score of accuracy was 1.06 and 1.62 by cholangiogram and 0.81 and 0.87 by ultrasound (p less than 0.05). Intraoperative ultrasonography was found to be more sensitive in detecting small CBD stones when compared with intraoperative cholangiogram.