Felis ISSN 2398-2950

Cerebrospinal fluid: cell count and differential

Contributor(s): Prof Bernard Feldman, Karen L Gerber


  • Nucleated cell numbers generally increase in acute inflammations and some other conditions.
  • Differential counts of nucleated cells essential to aid in diagnosis of central nervous system (CNS) pathology.


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  • Total cell count performed using a Neubauer hemocytometer. Apply undiluted CSF to the chamber. The total number of cells in 9 large squares (1 large square = 1 square mm) multiplied by 1.1 = cell count/ul .
  • To perform a differential count the cells must be concentrated using a sedimentation chamber or a cytocentrifuge.
  • For the sedimentation technique, construct a sedimentation chamber using a plain vacutainer glass tube with the end cut off. Dip the smooth end of the tube in melted wax or silicone grease and place on a warm slide. Place 1-3ml of CSF on the chamber and allow to settle in the fridge for 30 minutes to 2 hours.
  • Carefully aspirate the supernatent off and remove the cylinder.
  • Blot off any remaining liquid by touching the center of the sedimentation site with blotting/absorbent paper. Air dry the sample and fix in methanol.
  • Direct smears are only useful for extremely cellular samples - must smear immediately and fix in methanol.
  • Stain smears with Romanowsky stain Staining techniques: Romanowsky-type stains.


  • Sedimentaion chamber: standard.
  • Cytocentrifuge: specialist laboratory.

Technique (intrinsic) limitations

  • Cell counts may be falsely elevated due to blood contamination.

Result Data

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Further Reading


Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Mayhew I G & Beal C R (1989) Techniques in analysis of cerebrospinal fluid. In - Symposium on Advances in Veterinary Neurology. Veterinary Clinics of North America 10(1), 155-176.

Other sources of information

  • Brobst D & Bryan G (1989) Cerebrospinal fluid. In: Diagnostic Cytology of the Dog and Cat. 1st edn. Eds R L Cowell and R D Tyler. American Veterinary Publications Ltd.