Adequacy in pleural effusion: What is the minimum volume required for detection of malignant cells?

We recommend 13.5 ml as the minimum volume cut-off for a satisfactory pleural effusion cytology report. Below this volume, the false-negative rates increase, and the specimen may be deemed as limited for a conclusive diagnosis. As the volume rises above this threshold volume, the false negativity rate decreases but does not significantly improve malignant cells' detection.