Diagnostic accuracy of effusion cytology.

The aim of this investigation was to report on the diagnostic accuracy of conventional effusion cytology. Cytological diagnoses of 300 pleural effusions and 300 ascites were compared with clinical and/or histological follow-ups of the respective patients. Sensitivity of our cytological diagnoses on pleural effusions was 50.0%, specificity 97.0%, positive predictive value 95.7%, and negative predictive value 86.4%. Sensitivity in ascitic effusions was 62.4%, specificity 98.0%, positive predictive value 100.0%, and negative predictive value 88.3%; 5.8% of diagnoses for pleural and 4.4% for peritoneal effusions were suspicious or doubtful. The overall false-positive rate was 0.5%, while the false-negative rate was 31.5%. False-negative results were due to sampling errors in 71% of pleural and 73% of peritoneal effusions and to screening errors in 29% and 27%, respectively. Our data and those from the literature show that diagnostic accuracy of effusion cytology is still unsatisfactory and should be improved. Therefore, the use of different adjuvant methods is recommended.