Appearance

Culture (and GS)

Cell Count (unit: 10^6 / L)

Crystal

DDx and Interpretation

Common Marker Normal Non-inflammatory Arthritis () (Gout in mono) !Septic Arthritis
Appearance yellow transparent yellow transparent exudative Opaque, exudative Bloody Translucent
Viscosity + + - variable variable
WBC count <200 200-2,000 >2,000 >80,000 (some says 50,000) 2,000 - 80,000
PMN <25% <25% > 50% >75% 50-75%
Next Step - Special Test Microscopy (Crystals) GS, C & S Cytology