Diagnostic value of intraductal ultrasonography and brush cytology on differentiating malignant and benign biliary stricture

Abstract

Objective To investigate the diagnostic value of intraductal ultrasonography (IDUS) with or without brush cytology on distinguishing malignant from benign biliary stricture. Methods The data of patients with biliary stricture, who underwent endoscopic retrograde cholangiography(ERC) and IDUS in Drum Tower Hospital from September 2007 to October 2015 were retrospectively analyzed. Features of IDUS images and results of brush cytology were compared with postoperative histological results to evaluate the diagnostic yield of IDUS and brush cytology on differential diagnosis of malignant biliary stricture. Results A total of 230 patients with biliary stricture underwent ERC and IDUS, and 206 patients meanwhile received brush cytology, including 84 cases of malignant biliary stricture. Of the 230 patients, 87 cases underwent surgery, and 75 revealed malignant results, including 65 cases of cholangiocarcinoma, 8 cases of pancreatic adenocarcinoma, and 2 cases of periampullary adenocarcinoma. Using postoperative pathologic results as the gold standard, 72 malignant and 9 benign biliary strictures were correctly diagnosed by IDUS. The sensitivity, specificity, positive predictive value, and negative predictive value of IDUS for diagnosis of malignant biliary stricture was 96.0%, 75.0%, 96.0%, and 75.0%, respectively. Sixty-five patients underwent IDUS with brush cytology during ERC before surgery, and 56 out of 65 showed malignant results. Thirty-one malignant and 9 benign biliary stricture were correctly diagnosed by brush cytology. The sensitivity, specificity, positive predict value, and negative predict value of brush cytology for diagnosis of malignant biliary stricture was 55.4%, 100%, 100%, and 26.5%, respectively. If brush cytology combined with IDUS to diagnose malignant biliary stricture, the sensitivity rose up to 94.6%, while the specificity went down to 77.8%, and the positive and negative predictive value was 96.4% and 70.0%, respectively. Conclusion IDUS exhibited excellent sensitivity and specificity, while brush cytology revealed perfect specificity and positive predictive value on diagnosis of malignant biliary stricture. If IDUS combined with brush cytology, the sensitivity and negative predictive value could rise significantly, while the specificity and positive predictive value mildly went down, which suggested that IDUS remained a certain degree of over judgment and false positive rate. Key words: Endosonography; Cholangiopancreatography, endoscopic retrograde; Biliary stricture; Brush cytology