Cytologic evaluation of serous effusions. Processing techniques and optimal number of smears for routine preparation

A double-blind retrospective review of 90 pleural and ascitic fluids was performed to determine the optimal number of smears necessary to produce an accurate evaluation, and to analyze the utility of different preparation techniques. Each case had four Papanicolaou-stained smears (two alcohol fixed and two Saccomanno fixed) and one Diff-Quik-stained, air-dried smear. Forty cases originally were reported as positive (37 adenocarcinoma, 1 lymphoma, and 2 Pneumocystis carinii) and 50 were reported as negative. The results showed that the diagnostic yield of evaluating five smears compared with three (one of each preparation) is identical. Air-dried smears were the most sensitive in identifying malignant cells and infectious organisms. It is concluded that (1) the diagnostic accuracy is enhanced by the use of several preparation techniques to include air-dried smears and (2) when variable processing methods are used, the evaluation of more than three smears does not increase the diagnostic yield.