Accuracy and Added Value of Triage Beyond Segregating Potentially Neoplastic Effusions in Immediate Wet Preparation

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Objective: To study the accuracy and value of immediate wet preparation (WP) procedure on effusion and washing cytologic specimens. Study Design: Two hundred specimens were identified over 3 months in our cytology laboratory, including 102 pleural effusion, 59 peritoneal effusion, 28 pelvic washing and 11 pericardial fluid specimens. WP slides were prepared, stained with toluidine blue (TB) and evaluated. Findings were reported as negative, suspicious or positive for malignant cells. For negative specimens, the remaining prepared slides were stained together. For suspicious or positive interpretation, slides were stained separately. Accuracy and additional benefits from this immediate triage step were studied. Results: Interpretation of slides resulted in 152 negative, 34 positive and 14 suspicious for malignancy. Analysis for additional values resulted in immediate interpretation relayed to clinicians, additional fluid centrifuged for adequate sediment in samples with scant cellularity, selection of bloody specimens for acid washing procedures, selection of cases to optimize cell block preparation when pivotal histologic evaluation or immunohistochemistry was anticipated and selection of cases for potentially needed ancillary studies. Accuracy, sensitivity, specificity and positive and negative predictive values were high. Conclusion: WP using the TB is accurate, sensitive and highly specific and has considerable value beyond segregating potential neoplastic cases.