S76 Does IDUS Improve Diagnostic Yield of Brush Cytology in Malignant Biliary Strictures? A Systematic Review and Meta-Analysis

Introduction: Brush cytology during endoscopic retrograde cholangiopancreatography is widely used for diagnosing malignant biliary strictures but suffers from low sensitivity. Intraductal ultrasound (IDUS) offers high-resolution imaging that can help target suspicious areas, potentially improving the diagnostic yield of brush cytology. However, the added value of IDUS-guided brush cytology over brush cytology alone remains unclear. We conducted a meta-analysis to evaluate whether IDUS guidance enhances the diagnostic performance of brush cytology in detecting malignant biliary strictures. Methods: A systematic search was conducted in PubMed, Ovid, and Cochrane to identify studies comparing IDUS-guided brush cytology vs brush cytology alone for the diagnosis of malignant biliary strictures. Studies reporting diagnostic outcomes such as sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were included. Pooled outcomes were calculated using a random-effects model, and results were expressed as relative risk (RR) with 95% confidence intervals (CI). Statistical heterogeneity was assessed using the I² statistic. Results: Five studies with a total of 663 patients were included in the meta-analysis (IDUS-guided brush cytology: N = 384; brush cytology alone: N = 279). IDUS-guided brush cytology was associated with significantly improved diagnostic performance. The RR for sensitivity was 1.85 (95% CI: 1.36–2.53; P < 0.001; I² = 71.8), and for negative predictive value, RR was 1.44 (95% CI: 1.15–1.81; P = 0.002; I² = 66.4). Diagnostic accuracy was also higher with IDUS-guided brush cytology (RR 1.27, 95% CI: 1.07–1.50; P = 0.007; I² = 75). However, specificity (RR 0.88, 95% CI: 0.81–0.97; P = 0.012; I² = 61.5) and positive predictive value (RR 0.89, 95% CI: 0.83–0.95; P < 0.001; I² = 16.1) were slightly lower in the IDUS-guided brush cytology group. Conclusion: IDUS-guided brush cytology significantly improves the diagnostic sensitivity, negative predictive value, and overall accuracy for detecting malignant biliary strictures compared to brush cytology alone. These findings support the adjunctive use of IDUS during endoscopic retrograde cholangiopancreatography to enhance diagnostic yield and better guide clinical management.