Background and aim: Accurately differentiating malignant diseases from benign ones in patients having bile duct obstruction is of significant importance and remains a major clinical problem. This study investigated the diagnostic yield of endoscopic retrograde cholangiography/intraductal ultrasound (ERC/IDUS) in distinguishing malignant from benign bile duct obstruction and assessed some image findings from ERC/IDUS which might be useful in differentiation.
Methods: From January 2008 to January 2015, patients who underwent ERC/IDUS for bile duct obstruction were enrolled. Patient's ERC/IDUS diagnosis was compared with the final diagnosis determined by pathologic findings and/or clinical outcome of follow-up.
Results: One hundred and ninety-three patients with bile duct obstruction were included. IDUS correctly identified 94 of 97 malignant diseases and 76 of 96 benign diseases with sensitivity, specificity, and accuracy rate of 96.91, 79.17, and 88.08 %, respectively. Additionally, the accuracy rate of IDUS for diagnosis of proximal bile duct obstruction was higher than that of distal bile duct obstruction (98.08 vs. 82.73 %, p = 0.006). Besides, there was a significant difference in the length at the obstruction site between benign and malignant diseases (13.76 ± 7.37 vs. 19.97 ± 11.37 mm, p < 0.001) as well as thickness of bile duct wall at the site of obstruction (3.06 ± 0.92 vs. 7.03 ± 3.70 mm, p = 0.008). Biliary wall thickness >7 mm without extrinsic compression had a positive predictive value (PPV) of 100 % for including malignancy, while length ≧20 mm demonstrated a PPV of 93.44 %.
Conclusions: ERC/IDUS is effective in distinguishing malignant from benign bile duct obstruction, thus helping in further clinical management.
Keywords: Accuracy; Bile duct obstruction; Endoscopic retrograde cholangiopancreatography; Intraductal ultrasound; Length; Wall thickness.