Evaluation of Use of RPMI Medium to Preserve Cell Morphology for Pleural/Peritoneal Fluid Cytology

INTRODUCTION: Cytologic evaluation is the best way to detect the presence of malignancy in body cavity fluids. Roswell Park Memorial Institute (RPMI) medium or RPMI 1640 is used in cell culture, tissue culture, and also to improve the cellularity and morphology of CSF cytology specimens. OBJECTIVES: To determine whether RPMI medium can be used to preserve cell morphology in pleural/peritoneal effusion samples. METHOD AND MATERIAL: The study was conducted on 30 pleural/peritoneal fluid samples received routinely during 2 months for diagnostic purposes in our department. The samples were divided into four parts. One-fourth of the sample was directly refrigerated and the other fourth was at room temperature. In the other two parts, an equal volume of RPMI media was added, and one was kept at room temperature and the other refrigerated. These cytospin-prepared Giemsa-stained smears were examined for cell morphology, cellularity, and occurrence of bacterial colonies at 24 h, 48 h, 72 h, and 1 week, respectively. RESULT: Refrigerated RPMI medium is the best preservative for pleural/peritoneal samples; however, samples with RPMI at room temperature were equivalent/even worse than the simple refrigerated sample.