Peritoneal Fluid Analysis

Peritoneal fluid is a liquid that acts as a lubricant in the abdominal cavity.

Why Get Tested?

The purposes of the tests are to help diagnose:

  • the cause of peritonitis, an inflammation of the membrane lining the abdomen,
  • peritoneal fluid accumulation, where fluid builds up in the abdomen or around internal organs.

What does the test result mean?

The tests result helps determine whether the fluid is a transudate or exudate.


Most ascitic fluids are transudates and are caused by either congestive heart failure or hepatic cirrhosis. Typical fluid analysis results include:

  • Physical characteristics—fluid generally appears clear or straw-colored
  • Protein—less than 3 g/dL
  • Albumin level—low (typically evaluated as the difference between serum albumin and peritoneal fluid albumin, termed serum-ascites albumin gradient, or SAAG; values above 1.1 g/dL are considered evidence of a transudate.)
  • Lactate dehydrogenase (LD) fluid/serum ratio—less than 0.6
  • Glucose—equal to glucose level in the blood
  • Cell count—few cells are present, usually lymphocytes
  • Specific gravity—less than 1.015
  • Physical characteristics—fluid may appear cloudy
  • Protein—greater than 3 g/dL
  • Albumin level—higher than in transudates (typically with a SAAG less than 1.1 g/dL)
  • Lactate dehydrogenase (LD) fluid/serum ratio—greater than 0.6
  • Glucose—less than 60 mg/dL
  • Cell count—increased
  • Specific gravity—greater than 1.015

Exudates can be caused by a variety of conditions and diseases and usually require further testing to aid in the diagnosis. Please talk to your doctor to see what additional tests are needed.


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