Clinicopathological study of serous effusions - Comparison between conventional smear and cell block technique: A cross-sectional study

Background: Serous effusions are a common clinical finding in various pathological conditions, and cytological examination plays a crucial role in determining their etiology. Conventional smear cytology has been the traditional method for effusion analysis, but its limitations have prompted the exploration of complementary techniques such as the cell block (CB) method. This study aimed to compare the cytological features of conventional smear and CB methods in body fluids and assess their ability to diagnose malignancy. Methods: A total of 250 patients with serous effusions (126 pleural, 109 ascitic, and 15 pericardial) were included in the study. All samples were processed using both conventional smear and CB methods. The cytological features, diagnostic categorization (inflammatory, suspicious, or malignant), and additional findings were compared between the two methods. Using the CB method as the gold standard, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of conventional smear for malignancy diagnosis were calculated. Results: Using the conventional smear method, 77.6% of samples were diagnosed as inflammatory, 10.4% as malignant, and 12% as suspicious. In contrast, the CB method identified 75.6% as inflammatory, 23.6% as malignant, and only 0.8% as suspicious. Of the 30 suspicious cases by conventional smear, the CB method definitively classified 18 (60%) as malignant and 12 (40%) as inflammatory. The conventional smear method demonstrated a sensitivity of 38.98%, specificity of 98.43%, positive predictive value of 88.46%, negative predictive value of 83.93%, and overall accuracy of 84.4% for malignancy diagnosis. Conclusion: The CB method significantly enhances diagnostic accuracy in serous effusions, particularly for malignancy detection, with a higher sensitivity and resolution of suspicious cases compared to conventional smear. While conventional smear remains valuable as a rapid screening tool with high specificity, the complementary use of both methods represents an optimal approach to effusion cytology in clinical practice.