Table 13-1.

Classification of Abnormal Synovial Fluid

	Hemarthrosis	Nonsuppurative Arthropathy	Suppurative Arthropathy
Appearance	Red, cloudy, or xanthochromic	Clear	Cloudy
Protein	Increased	Normal to decreased	Normal to increased
Viscosity	Decreased	Normal to decreased	Normal to decreased
Mucin clot	Normal to poor	Normal to poor	Fair to poor
Cell count (/μL)	Increased nucleated cells; red blood cells	1000 to 10,000	5000 to >100,000
Neutrophils	Relative to blood	<10%	>10 to 100%
Mononuclear cells	Relative to blood	>90% (both lymphocytes and large mononuclear cells)	10 to <90%
Comments	Erythrophagia helps confirm previous hemorrhage.	Synoviocytes are typically seen along with macrophages in thick sheets.	Septic and nonseptic etiologies. Bacteria are rarely observed in infected joints.