Predictive Clinical Factors for Endoscopic Ultrasound Diagnosis in Undiagnosed Common Bile Duct Dilatation on...

Introduction Dilatation of the common bile duct (CBD) without an identifiable etiology on computed tomography (CT) or magnetic resonance cholangiopancreatography (MRCP) is a common clinical challenge and may lead to repeated investigations and unnecessary invasive procedures. Endoscopic ultrasound (EUS), due to its close proximity to the biliary tree, has emerged as a promising diagnostic tool. This study aimed to evaluate the diagnostic yield of EUS in patients with unexplained CBD dilatation on CT/MRCP and identify clinical predictors of positive EUS findings. Methods This was a prospective observational study conducted at a tertiary care center in Western India from January 2023 to January 2024. Patients with a dilated CBD (>6 mm with gallbladder in situ or >8 mm post-cholecystectomy) and no identifiable cause on CT or MRCP were included. EUS was performed within two weeks of cross-sectional imaging, and findings were confirmed with ERCP or biopsy where indicated. Clinical, laboratory, and imaging variables were analysed to identify predictors of positive EUS diagnosis. Results Out of 525 patients who underwent EUS, 75 met the inclusion criteria. The mean age was 50.6 ± 15.9 years, and 56% were female. A definitive diagnosis was established in 41 patients (54.7%), with choledocholithiasis (33.3%) and benign biliary strictures (10.7%) being the most common etiologies. Multivariate analysis identified age ≥49.5 years, alkaline phosphatase ≥181 IU/L, and CBD diameter ≥8.75 mm on cross-sectional imaging as independent predictors of a positive EUS diagnosis. The combined area under the receiver-operating characteristic curve (AUROC) for these variables was 0.746. Conclusion EUS established a definitive diagnosis in approximately half of patients with unexplained CBD dilatation. Its ability to detect small stones makes it a valuable diagnostic modality. Age, elevated alkaline phosphatase, and increased CBD diameter were significant predictors of diagnostic yield, supporting the selective use of EUS in this population.