Diagnostic Efficacy of Brush Cytology in the Evaluation of Extrahepatic Bile Duct Strictures: Experience from a Tertiary Care Centre in Northern India

Background: Endoscopic evaluation is critical in assessing the cause of obstructive jaundice. Biliary brushings during endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography (PTC) are widely used for obtaining a tissue sample. This study was undertaken to investigate the role of endoscopic biliary tract brush cytology as a diagnostic tool in extrahepatic biliary strictures. Materials and Methods: During the 6-year study period, 80 jaundiced patients underwent ERCP (n=63) / PTC (n=17) along with cytological evaluation of biliary brushings. Demographic data and relevant clinico-radiological details were retrospectively retrieved from institutional records. The corresponding cytological smears were re-evaluated and classified as: (i) unsatisfactory/inadequate; (ii) negative (including benign and reactive); (iii) suspicious for malignancy; (iv) positive for malignancy. Cytology results were compared with final diagnosis (defined as either definitive tissue diagnosis or clinico-radiological follow-up), and sensitivity (SN), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy (DA) were calculated. Results: The age group of patients ranged from 15 to 85 years, with mean age of presentation being 52.7 years. Cytologic diagnosis was: positive for malignancy in 23 (26.7%), suspicious in 8 (9.3%), and benign/reactive/negative in 52 (60.5%) cases. In the 61 cases where the final diagnosis was available, the overall SN, SP, PPV, NPV, and DA of biliary brush cytology were 68.57%, 92.31%, 92.31%, 68.57%, and 78.69%, respectively. There was no significant difference in DA of brushings obtained at ERCP compared to those from PTC. Conclusion: We found directly-smeared brush cytology to be diagnostically reliable, moderately sensitive, and highly specific for diagnosing common bile duct lesions encountered at ERCP/PTC.