Background
There is still a debate about the utility of intraoperative cholangiography (IOC) or laparoscopic ultrasonography (LUS) for detection of occult choledocholithiasis during laparoscopic cholecystectomy (LC). The aim of this study was to assess the value of IOC combined with LUS for detection of occult common bile duct (CBD) stones at LC.
Material and Method
From Dec 2002 to Aug 2006, 103 patients with moderate risk of CBD stones underwent IOC and LUS simultaneously during LC. The physician teams for the two different procedures were blinded by each other. The sensitivity, specificity, accuracy, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio were calculated by several contingency tables that cross-tabulated the results of each technique with those of the gold standard.
Results
The success rate of IOC and LUS were 91.3% and 100% respectively and the time required for LUS was significantly shorter (P<0.01). The visualization of intrapancreatic part of CBD by IOC (97.3%) was significantly higher than LUS (73.8%). The sensitivities, specificities, accuracies, positive and negative predictive values, positive and negative likelihood rations identifying occult CBD stones were 75.0%, 98.7%, 92.2%, 95.5%, 91.4%, 57.7 and 0.253 by IOC, and 82.1%, 98.7%, 94.2%, 95.8%, 93.7%, 63.2 and 0.181 by IUS respectively. The McNemar test showed no significant difference between two methods. The sensitivity of IOC combined with LUS was 92.9%, which was greater than that of IOC and LUS taken separately.
Conclusions
LUS is usually performed in case where IOC has failed or is contraindicated. The combination of both methods maximizes intraoperative detection of occult CBD stones and should at least be recommended as two complementary methods.

Keywords: Laparoscopy - methods, Intraoperative Period - methods, Gallstones - ultrasonography, Common Bile Duct - ultrasonography, Combined Modality Therapy - methods, Choledocholithiasis - ultrasonography, Cholecystectomy, Laparoscopic - methods, Cholangiography - methods, Aged, 80 and over, Predictive Value of Tests, Ultrasonography - methods, young adult