Combined Liquid-Based Cytology and Conventional Smear Provides Better Sensitivity and Adequacy Rates After Endoscopic Ultrasound-Guided Tissue Acquisition of Abdominal Masses: A Systematic Review and Meta-Analysis.

Background and Aims: Endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) or biopsy (FNB) is the standard method for diagnosing abdominal masses, but sample inadequacy and diagnostic accuracy remain challenges. Conventional smear (CS) and liquid-based cytology (LBC) are standard processing methods, yet their comparative effectiveness and potential combined benefit remain unclear. We performed a systematic review and meta-analysis to evaluate and compare the diagnostic performance and adequacy of CS, LBC, and their combination. Methods: A systematic search was conducted in Medline, Embase, and CENTRAL on 17 November 2024. Studies comparing CS, LBC, or their combination following EUS-FNA/FNB for abdominal masses were included. Diagnostic parameters, including sensitivity, specificity, accuracy, and inadequacy rates, were extracted and analyzed. Methodological quality was assessed using QUADAS-2. Results: 16 studies (2128 patients) were included. Sensitivity for pancreatic masses was 71.4% (CI: 62.9-78.7) for CS, 74.7% (CI: 64.3-82.8) for LBC, and 86.2% (CI: 82.4-89.3) for combined methods (p = 0.001). For all abdominal masses, sensitivity was 76.3% (CI: 67.9-83.0) for CS, 73.6% (CI: 65.6-80.2) for LBC, and 88.0% (CI: 84.0-91.2) for combined methods (p ≤ 0.006). Specificity was nearly 100%. Inadequacy rates were lowest for combined methods (1.5%, CI: 0-36.2), when compared to LBC (7.7%, CI: 2.7-20.4) and CS (4.4%, CI: 2.4-7.9). Moderate bias risk was noted, primarily due to incorporation bias. Domain 3 (reference standard) of QUADAS was uniformly moderate-risk across studies. Conclusions: Combining CS and LBC methods improves diagnostic sensitivity and reduces sample inadequacy after EUS-guided tissue acquisition for abdominal masses, particularly pancreatic lesions. Clinical guidelines should consider recommending the combined approach to enhance diagnostic yield and clinical outcomes.