What is the role of arthrocentesis and synovial fluid analysis in the diagnosis of gonococcal arthritis?

Updated: Jul 31, 2018
  • Author: Rachel Robbins, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Arthrocentesis is mandatory in cases of suspected septic arthritis. Laboratory tests typically performed on synovial fluid include cell count, crystal analysis, Gram stain, and culture.

The cell count is usually higher than 50,000 WBC/µL (with polymorphonuclear leukocytes [PMNs] typically accounting for more than 90%). Synovial fluid with this much inflammation may appear purulent. Gram-negative intracellular organisms may be demonstrated, albeit in less than 25% of synovial fluid aspirates. Synovial fluid should be cultured on prewarmed chocolate agar for highest yield (findings are positive in only 50% of patients with gonococcal arthritis and 25-30% of those with DGI).

Repeat arthrocentesis should be performed when inflammatory synovial effusions recur in order to remove inflammatory mediators, debris, and purulence. Surgical drainage may be needed in joints refractory to drainage via arthrocentesis; however, it is rarely necessary in patients with gonococcal arthritis.


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