Examination of Body Fluids: Preparation of Slides and Cell Morphology

Extract

Specimens concentrated by centrifugation or cytocentrifugation are used to perform differential counts and assess cell morphology on body fluids. Using standard centrifugation, the specimen is centrifuged, the supernatant removed, and a slide made from the buffy coat if RBCs or the concentrated cells of the centrifugate are present.. In cytocentrifugation the specimen is transferred to a cytofunnel assembly. The specimen is centrifuged at 1000 RPM for 10 minutes allowing fluid to be absorbed into filter paper and cells to be concentrated in a small area of the slide. The slides prepared by either concentration method should be allowed to air dry and are then stained with Wright or Wright-Giemsa stain prior to examination. If it is not possible to prepare cell concentrations to assess morphology of nucleated cells and cells are differentiated while the cell count is performed, a lysing agent that enhances the nucleus of cells must be used to determine the category of the cells. In this article, preparation of slides refers to cytocentrifugation.

To prepare a monolayer cytocentrifuge slide, which is optimal for nucleated cell identification, use the nucleated cell count (not the RBC count) to determine the saline dilution for the cytocentrifuge preparation. A consistent amount of undiluted or diluted fluid should be used to prepare a cytocentrifuge slide—usually 0.25 mL or five drops. A good monolayer preparation can be obtained if the nucleated cell count is less than 200/μL. If the nucleated cell count is greater than 200/μL, divide the cell count by 100 to…

ABBREVIATIONS: ALL = acute lymphoblastic leukemia; AML = acute myeloblastic leukemia; CNS = central nervous system; CSF = cerebrospinal fluid; HIV = human immunodeficiency virus; RBC = red blood cell; WBC = white blood cell.