Transudate

• Low protein and low celularity
• Clear
• Specific gravity <1.018
• Total protein < 25g/L
• Nucleated cells <0.5 x 10e9/L
• Mesothelial cells, macrophages, low numbers of non-degenerate neutrophils
• Typically very high volume of fluid

• Due to:
  • Decreased colloid osmotic pressure
  • Renin - angiotensin system activation
  • Hypoalbuminaemia secondary to glomerular or hepatic disease or GI loss (globulins also low)
  • Prolonged portal hypertension and formation of secondary collateral circulation