Diagnostic yield of biliary brush cytology via endoscopic retrograde cholangiopancreatography: a 7-year tertiary center experience.

Background: biliary brushing cytology during endoscopic retrograde cholangiopancreatography (ERCP) was used to assess the nature of a biliary stricture. Its low sensitivity challenges the exclusion of malignancy through this technique. The aim of this study was to evaluate the diagnostic yield of brush cytology in biliary strictures and to identify predictive factors associated with a positive diagnosis of malignancy.

Methods: an observational retrospective study was performed in a tertiary center. All adult patients undergoing a biliary brushing during ERPC from 2016 to 2022 were included. Logistic regression analyses were performed to identify predictive factors for positive brush cytology.

Results: a total of 5,309 patients underwent ERCP within the evaluated period. Out of these, biliary brushing was performed in 518 patients, including 568 cytology samples; 57.7 % (299) were male, with a median of 74 (64-84) years of age. Within the cohort, 24 % (126) had benign strictures and 76 % (392) had malignancy, of which the most common etiologies were pancreatic cancer 42.5 % (220/518), followed by cholangiocarcinoma 22.6 % (117/518). The sensitivity, specificity, positive predictive value, and negative predictive value were 48 %, 98 %, 98 % and 37 %, respectively. Sensitivity was 45 % and 52 % in pancreatic adenocarcinoma and cholangiocarcinoma, respectively. Older age (OR 1.02, 95 % CI: 1.01-1.03, p = 0.01) and higher bilirubin levels (OR 1.05, 95 % CI: 1.03-1.08, p < 0.001) were independent predictors for brush cytology positivity. The post-ERCP complication rate was 9.7 % (45/518).

Conclusions: biliary brushing cytology during ERCP is a safe procedure with a low sensitivity and high specificity. Older age and higher bilirubin levels are associated with positive biliary cytology.