UMEM Educational Pearls

Category: Procedures

Title: Paracentesis Part II- Ascites Fluid Analysis

Keywords: paracentesis, ascites, analysis (PubMed Search)

Posted: 9/27/2008 by Michael Bond, MD (Updated: 12/7/2019)
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Paracentesis Part II- Ascites Fluid Analysis:

See last weeks procedure pearl for some hints on doing a paracentesis..

Now that you have the fluid what should you send it for:

  • Cell Count
  • Gram Stain and Culture
  • Amylase (normal value is half serum)
  • Albumin
  • Consider cytology if  cancer is a consideration

Now for the analysis:

  • WBC Count >250 PMNs generally accepted as consistent with infection.  Especially if there is more than 70% PMNs which is the upper limit of normal. SAAG (Serum - Ascites Albumin Gradient) an easy calculation to differentiate what the cause of the ascites might be from:
    • Subtract the patient's ascites albumin from the serum albumin (Serum Albumin - Ascites Albumin = SAAG)
    • SAAG > 1.1 mg/dL(Due to items that increase portal pressures)
      • Cirrhosis
      • Alcoholic Hepatitis
      • Cardiac Ascites
      • Hepatic Failure
      • Budd-Chiari Syndrome
      • Portal Vein Thrombosis
      • Myexdema
      • Others
    • SAAG < 1.1 mg/dl (due to intraabdominal forces causing increased oncotic pressure)
      • Tuberculosis Peritonitis
      • Pancreatitic Ascites (typically while have elevated amylase in ascitic fluid)
      • Bowel Obstruction
      • Nephrotic Syndrome
      • Biliary Ascites
      • others

** Corrected definition of SAAG as it was initially reversed.  Thanks to Dr. McCurdy on his proof reading.