Abstract: Objective To explore and analysis the values of liquid based cytology combined with agar paraffin double embedding section method for pathological detection of pleural and ascitic fluid sediment. Methods From March 2019 to September 2022, 92 cases of patients with pleural and ascitic fluid who were diagnosed and treated at a certain hospital were selected as the research subjects. All patients were underwent liquid based cytology testing of pleural and ascitic fluid combined with agar paraffin double embedding section method for pleural and ascitic fluid sediment. Pathological biopsy were also performed to determine the diagnostic value. Results There were 54 cases were diagnosed as malignant tumors and 38 cases were diagnosed as benign tumors by pleural and ascitic fluid based cytology in the 92 cases. The sensitivity and specificity of pleural and ascitic fluid based cytology in diagnosing malignant tumors were 85.48% and 96.67%, respectively. The sensitivity and specificity of agarose paraffin double embedding sections in the diagnosis of malignant tumors were 88.71% and 100.00%, respectively, and 56 cases of malignant tumors and 36 cases of benign tumors were detected by the method. The sensitivity and specificity of agarose paraffin double embedding section detection of pleural and ascitic fluid sediment in diagnosing malignant tumors were 98.39% and 100.00%, respectively, and 61 cases of malignant tumors and 31 cases of benign tumors were detected by the method. The positive rates of human epidermal growth factor receptor 2, synaptophysin, and chromaffin A expression in malignant tumor patients were 40.32%, 41.94%, and 43.55%, respectively, which were significantly higher than those in benign tumor patients （10.00%, 13.33%, 10.00%, P<0.05）. The sensitivity of the combination of liquid based cytology detection of pleural and ascitic fluid and agar paraffin double embedding section method for the diagnosis of benign and malignant tumors is higher than that of single detection （P<0.05）, and there is no significant difference in the diagnostic specificity of different detection methods （P>0.05）. The ROC curve analysis showed that the diagnostic curve for benign and malignant tumors using liquid based cytology combined with agar paraffin double embedding section method for pleural and ascitic fluid sediment were 0.883. Conclusion The application of liquid based cytology combined with agar paraffin double embedding section method in pathological detection of pleural and ascitic fluid can improve diagnostic sensitivity, it can also maintain very high diagnostic specificity, and have great value in determining the benign and malignant nature of primary tumors in patients.

Key words: pleural and ascitic fluid, liquid based cytology, hydrothorax and ascites sediment, Agar paraffin double embedding section, malignant tumors, benign tumor