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.