Endoscopic Ultrasonography for Diagnosing Common Bile Duct Stones With Negative Initial Imaging: A Multicenter Prospective Exploratory Study

BACKGROUND: Common bile duct stones (CBDSs) can cause severe conditions. Endoscopic retrograde cholangiopancreatography (ERCP) is recommended but has a high rate of adverse events. However, some suspected cases do not have stones, requiring accurate evaluation in even high-likelihood patients. Endoscopic ultrasonography (EUS) offers high diagnostic performance. This study aimed to clarify the utility of EUS for diagnosing CBDSs in patients with strong suspicion of CBDSs. METHODS: This multicenter prospective exploratory study included patients with a high likelihood of CBDSs according to the American Society of Gastrointestinal Endoscopy guidelines, in whom CBDSs were not detected on initial imaging. EUS was subsequently performed, and diagnostic performance was assessed using ERCP findings or clinical course. RESULTS: Forty-eight patients were analyzed. EUS identified CBDSs in 21 and no stones in 27. A final diagnosis of CBDS was confirmed in 19 patients. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of EUS (95% confidence interval) were 95.8% (85.7%-99.5%), 100% (75.1%-100%), 93.1% (77.2%-99.2%), 90.5% (69.6%-98.8%), and 100% (81.7%-100%). Among patients without CBDSs at final diagnosis, unnecessary ERCP was avoided in 79.3%. CONCLUSIONS: EUS would accurately diagnose CBDSs in high-likelihood patients with negative initial imaging, potentially reducing unnecessary ERCPs.