Diagnostic yield of endoscopic ultrasound in dilated common bile duct with non-diagnostic cross-sectional imaging

Abstract

Biliary dilatation without obvious etiology on cross sectional imaging warrants further investigation. This study aimed to assess yield of endoscopic ultrasound in providing etiologic diagnosis in such situation. Prospective cohort of consecutive patients with biliary dilatation & non diagnostic computed tomography (CT) and /or magnetic resonance imaging (MRI) underwent endoscopic ultrasound (EUS) with/without fine needle aspiration cytology (FNAC) and were followed clinically, biochemically with/without radiology for up to six months. The findings of EUS were corroborated with histopathology of surgical specimens and endoscopic retrograde cholangiography (ERCP) findings in relevant cases. Median age of 121 patients completing follow up was 55 years. 98.2% patients were symptomatic and median common bile duct (CBD) diameter was 13 mm. EUS was able to identify lesions attributable for biliary dilatation in (67 out of 121) 55.4% cases with ampullary neoplasm being the commonest (29 out of 67 i.e. 43%). Multivariate logistic regression analysis identified jaundice as the predictor of positive diagnosis on EUS, of finding ampullary lesion and pancreatic lesion on EUS. EUS had sensitivity, specificity, positive predictive value and diagnostic accuracy of 95.65%, 94.23%, 95.65% and 95.04% respectively in providing etiologic diagnosis. Threshold value for baseline bilirubin of 10 mg%, for baseline CA 19.9 of 225 u/L and for largest CBD diameter of 16 mm were determined to have specificity of 98%, 95%, 92.5% respectively of finding a positive diagnosis on EUS. EUS provides considerable diagnostic yield with high accuracy in biliary dilatation when cross sectional imaging fails to provide etiologic diagnosis.