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. 2009 Oct 30:171–191. doi: 10.1016/B978-141604985-2.50011-6

TABLE 6-1.

Classification of Common Body Cavity Effusions Based on Fluid Characteristics

Effusion Type Color/Turbidity Total Protein (g/dl) Specific Gravity* WBC (# per μl) Predominant Cell Type (s)
General Conditions
Transudate Colorless/clear <2.5 <1.017 <1000

  • Mesothelial

  • Mononuclear phagocytes
Modified transudate Light yellow to apricot/clear to cloudy ≥2.5 1.017–1.025 >1000 Mononuclear cells
Exudate Apricot to tan/cloudy >3.0 >1.025 >5000

  • Neutrophils

  • Nonseptic (nondegenerate)

  • Septic (degenerate)
Specific Conditions
Chylous White/opaque >2.5 >1.017 Variable

  • Acute: Small lymphocytes

  • Chronic: Mixed population
Neoplastic Light yellow to apricot/clear to cloudy >2.5 >1.017 Variable

  • Reactive mesothelium

  • Neoplastic cells
Hemorrhagic Pink to red/cloudy >3.0 >1.025 >1000

  • Erythrocytes

  • Leukocytes similar to blood

  • Macrophages display erythrophagocytosis
Bilious Dark yellow or brown or green/opaque >3.0 >1.025 >5000 Mixed population with blue-green, brown, or yellow material phagocytized by macrophages
*

Note that measurement of specific gravity using a standard refractometer has not been validated for use with body cavity fluids, only urine. Therefore, values should be regarded with caution (George, 2001).