Clinical predictors of significant findings on EUS for the evaluation of incidental common bile duct dilation

Abstract

While endoscopic ultrasound(EUS) is highly accurate for the evaluation of common bile duct (CBD) dilation, the yield of EUS in patients with incidental CBD dilation is unclear. Serial patients undergoing EUS for incidental, dilated CBD (per radiologist, minimum >6mm objectively) from two academic medical centers, without active pancreaticobiliary disease or significantly elevated LFTs were evaluated. Multivariable logistic regression identified predictors of EUS with significant findings and a novel prediction model was derived from one center, internally validated with bootstrapping, and externally validated at the second center. Of 375 patients evaluated, 31 (8.3%) had significant findings including 26 choledocholithiasis, 1 ampullary adenoma, and 1 pancreatic mass. Predictors of significant findings with EUS included: age ≥70(OR 3.7, 95CI 1.5-10.0), non-biliary-type abdominal pain without chronic pain(OR 6.1, 95CI 2.3-17.3), CBD diameter ≥15 mm or ≥17mm with cholecystectomy(OR 6.9, 95CI 2.7-18.7), and prior ERCP(OR 6.8, 95CI 2.1-22.5). A point-based novel clinical prediction model was created: age ≥70=1, non-biliary-type abdominal pain without chronic pain=2, prior ERCP=2, CBD dilation=2. A score <1 had 93% (development) and 100% (validation) sensitivity and predicted a <2% chance of having a significant finding in both cohorts while excluding the need for EUS in ∼30% of both cohorts. Conversely, a score >4 was >90% specific for the presence of significant pathology. Less than 10% of patients undergoing EUS for incidental CBD dilation had pathologic findings. This novel, externally validated, clinical prediction model may reduce low-yield, invasive evaluation in nearly a third of patients.