What is the role of joint aspiration in the diagnosis of septic arthritis?

Updated: Sep 19, 2017
  • Author: John L Brusch, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Always perform joint aspiration under the most sterile conditions possible to prevent the introduction of infection.

Normal joint fluid is clear and colorless and produces a stringlike structure when ejected from a syringe, indicating normal viscosity. Infected joint fluid is typically yellow-green due to elevated levels of nucleated cells, and the cell count is usually markedly elevated, demonstrating a predominance of polymorphonuclear leukocytes. An evaluation of the synovial fluid (ie, via leukocyte count, appearance on Gram stain, polarizing microscopy examination, culture) is the most rewarding approach in assessing a potentially infected joint. Additional stains and/or cultures should be obtained depending on the differential diagnosis considered. [9, 21] Alterations in the glucose and protein concentration of the synovial fluid are nonspecific; these should not be measured routinely.


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