Synovial Fluid Analysis


 
Sign Normal GROUP 1 :
NON-Inflammatory
(Osteoarthritis, Hypothyroidism)
GROUP 2:
Inflammatory
(RA, Gout, CPPD, Spondylarthopathy)
GROUP 3:
Septic
Clarity Transparent Transparent Slightly opaque Opaque
Color Clear Yellow Yellow-opalescent Yellow-green
Viscosity High High Low Usually low
Culture (-) (-) (-) Often (+)
WBCs < 200 200-2000 2000-50,000 > 25,000
PMNs (%) < 25 < 25 > 50 > 75

 

Indications for Arthrocentesis:

Synovial Fluid Analysis: The single most useful diagnostic study in initial evaluation of monoarthritis:
  1. Suspicion of infection
  2. Suspicion of crystal-induced arthritis
  3. Suspicion of hemarthrosis
  4. Differentiating inflammatory from noninflammatory arthritis

 

Tests To Perform

  • Gram stain and cultures
  • Total leukocyte count/differential
    • Inflammatory vs. non-inflammatory
  • Polarized microscopy to look for crystals
  • Not really routinely:
    • Chemistry (glucose, total protein, LDH) unlikely to yield helpful information beyond the previous tests.