CSF Analysis
Also known as: Spinal fluid analysis
Formal name: Cerebrospinal fluid analysis
Related tests: Glucose, Total Protein, CBC (Complete Blood Count), Lactate, Protein Electrophoresis, Antibody Tests, AFB Smear and Culture, Blood Culture, Herpes, Lyme Disease, Rubella, Syphilis, West Nile Virus
Microscopic examination — Normal CSF has no or very few cells present and appears clear. If the CSF sample appears clear, a small drop of undiluted CSF is examined under a microscope, and cells are counted manually. If the number of cells present are very few (for example, 5 or less), the laboratory may or may not perform a cell differential (see below). If cells are numerous (such as greater than 5), a differential will most likely be done. To perform a differential, labs will often use a special centrifuge (cytocentrifuge) to concentrate the cells at the bottom of a test tube. A sample of the concentrated cells is placed on a slide, treated with special stain, and an evaluation of the different kinds of WBCs present is performed.
However, if the CSF is very cloudy or bloody, which can indicate the presence of many cells, the specimen may be run on an automated cell counter for cell enumeration. These samples may be cytocentrifuged, but if there are too many cells present in the centrifuged sample, an accurate differential may be difficult to perform. In those cases, the specimen may be diluted, cytocentrifuged, and then stained.
If cancer is suspected or has been previously diagnosed, the sample is usually cytocentrifuged regardless of the number of cells counted, and a differential is performed.
