Introduction

Extract

This series of articles will address the performance of cell counts and differential cell counts on the three most common categories of body fluids: cerebrospinal fluid (CSF), serous or body cavity fluids (pleural, pericardial, peritoneal), and synovial or joint fluids. Each has unique characteristics and cell counts, and differentials are performed for different purposes on each one. When a fluid is received in the laboratory, information that can be helpful in determining the cell counts is obtained from the gross appearance of the fluid. A point to be remembered is that the specimen is obtained by a physician who also observes the gross appearance of the fluid. This is especially significant in CSF if only one tube is obtained and it is bloody. Every body fluid should be examined—cell count performed and slide for evaluation of cell morphology prepared—immediately after collection since cells, especially neutrophils, begin disintegrating within 30 minutes.

Cytocentrifuge concentration of cell preparations improves cell identification over attempting to differentiate cells while performing hemacytometer cell counts. With appropriate dilution, a monolayer slide can be prepared to enhance morphology of cells. Cytocentrifuge concentration provides enough nucleated cells to perform a 100-cell differential count if the nucleated cell count is greater than 3/μL. Since there will be some cell yield even if the cell count is zero, important diagnostic information can be obtained especially in leukemic patients when blast cells may be present. The presence of red blood cells (RBCs) in fluids can interfere with nucleated cell morphology due to…

ABBREVIATIONS: AIDS = acute immunodeficiency syndrome; CSF = cerebrospinal fluid; HIV = human immunodeficiency virus; RBC = red blood cell.