摘要： Choledocholithiasis is usually diagnosed by one of several radiographic modalities prior to Endoscopic retrograde cholangiopancreatography(ERCP). Often, despite a radiographic diagnosis of a common bile duct (CBD) stone, no stone is found at ERCP, indicating that pre-procedure imaging may not be accurate. We compared the diagnostic accuracy of different imaging techniques in predicting choledocholithiasis, with ERCP as the gold standard. Methods: We prospectively entered information into a database for 4447 ERCP’s spanning 17 years, beginning in 2000, at an academic referral center. We retrieved 822 ERCPs performed for choledocholithiasis found on imaging. The imaging modalities showing choledocholithiasis were: 172 magnetic retrograde cholangiopancreatography’s(MRCP), 220 computed tomography(CT) scans, 219 ultrasounds (U/S), and 211 intra-operative cholangiograms (IOC). Given the presumed high pretest probability of choledocholithiasis predicted by these imaging studies, all patients underwent a biliary sphincterotomy and balloon or basket sweep of the CBD. Patients were divided into those with a dilated CBD (> 10 mm) and a non-dilated CBD (<Z 10 mm). Ultrasound: Of the 219 patients with stones on U/S, 163 actually had a stone(s) at ERCP, and 56 did not, for a likelihood, or positive predictive value (PPV), of 74%. That is, PPV Z True-positive/(True-positive + False-positive) Z 163/(163+56) Z 74%. Separating by bile duct diameter, for CBD > 10 mm, 95 patients had stones, while only 11 did not (PPV Z 90%). For CBD <Z 10 mm, 68 actually had stones, while 45 did not (PPV Z60%, pZ0.00005). See the attached table below for similar calculations for CT, MRCP, and IOC. Conclusion: The true incidence of CBD stones after so-called “positive imaging” is not as high as one would expect, with PPVs of only 74% for MRCP, 85% for CT, 74% for U/S, and 60% for an IOC. It is important to note that the ?nding of choledocholithiasis on any imaging platform should be interpreted with caution, and in the context of other data such as laboratory values and clinical presentation. CBD diameter > 10 mm was a statistically signi?cant predictor of a “true positive” imaging study on CT, US, and IOC, but not for MRCP. However, there was a trend toward better predictive value for larger duct diameters for MRCP as well, and we feel that MRCP ?ndings might reach statistical signi?cance if the sample size were slightly larger. These ?ndings, along with other clinical parameters, may enable exclusion of some patients from unnecessary ERCPs who might be at lower risk of CBD stones based on smaller duct diameter.