97 Performance Comparison Between Endoscopic Ultrasound/endoscopic Retrograde Cholangiopancreatography and Intraoperative Cholangiography for Detecting Choledocholithiasis

Abstract

INTRODUCTION: The diagnosis and management of choledocholithiasis have been evolving given multiple diagnostic modalities. One of these diagnostic modalities is intraoperative cholangiogram (IOC) which is typically performed during laparoscopic cholecystectomy for evaluation of choledocholithiasis. Our aim is to compare endoscopic ultrasound (EUS) to IOC in the accurate detection of a common bile duct stone using endoscopic retrograde cholangiopancreatography (ERCP) as gold standard for diagnosis. METHODS: A five-year retrospective single center study was performed for patients diagnosed with choledocholithiasis due to a positive IOC during laparoscopic cholecystectomy. These patients subsequently were tested with EUS and ERCP (Group 1). Analysis was also performed in which patients underwent IOC with subsequent ERCP without EUS (Group 2). We used ERCP as the gold standard to ascertain a percentage of true positives, true negatives, sensitivity, specificity and corresponding 95% exact confidence intervals. Demographic data and laboratory values (bilirubin and liver enzymes) prior to endoscopic procedure were also described. RESULTS: All of the 24 IOC positive patients (Group 1) were subjected to EUS and the majority of these patients underwent an ERCP. EUS detected 80% (8/10, 95% CI: 48.1–96.5) true positives and 92.3% (12/13, 95% CI: 67.5–99.6) true negatives among these IOC positive patients (Figure 1). 52 patients who underwent IOC and subsequent ERCP without EUS (Group 2). 43 of the 52 patients were positive to IOC. Nine IOC negative patients were examined with ERCP and 6 were negative. IOC detected 69.7% (30/43, 95% CI: 54.9–82.0) of true positives and 66.7% (6/9, 95% CI: 33.2–90.7) true negatives (Figure 1). With a sensitivity of 90.9% (95% CI: 75.7–98.1) and specificity of 31.6% (95% CI: 12.6–56.6), IOC resulted 30.2% (13/43, 95% CI: 18.0–46.1) false positives and 33.3% (3/9, 95% CI: 9.27–66.8) false negatives. CONCLUSION: Test performance of EUS in IOC-positive patients compared to test performance of IOC in patients not tested with EUS were comparable. However, with about a third of patients exposed to unnecessary ERCP, clinical practicality of IOC as the screening test is questionable. Large proportion of false positives is not desirable for a screening test with less than perfect sensitivity. Thus, EUS can help risk stratify patients and presumably avoid or minimize unnecessary ERCP risks to patients. Additional studies with large patient populations will be more conclusive.