Paracentesis Fluid Interpretation and SAAG (serum-ascites albumin gradient)

 • PMN ≥250/μL, (+) Ascites culture - Spontaneous bacterial peritonitis (SBP) (secondary peritonitis → polymicrobial)

 • PMN ≥250/μL, (-) Ascites culture - Culture negative neutrocytic ascites (CNNA)

 • PMN <250/μL, (+) Ascites culture - Non-neutrocytic bacterascites (NNBA) 

 • PMN <250/μL, (-) Ascites culture - Normal

 • Hemorrhagic ascites: RBC >50,000/mm3, often due to traumatic tap → correct PMN count by subtracting 1 PMN for every 250 RBCs

SAAG (serum-ascites albumin gradient) differentiates portal hypertensive vs. non-portal hypertensive ascites 97% of the time

SAAG ≥1.1 g/dL - Etiology related to portal hypertension: 

 • Cirrhosis (ascites fluid total protein [AFTP] <2.5 g/dL)

 • CHF (AFTP typically >2.5 g/dL)

 • Acute hepatitis (including EtOH)

 • Massive liver metastases

 • Hepatocellular carcinoma

 • Budd-Chiari syndrome

 • Portal vein thrombosis

SAAG <1.1 g/dL - Etiology not related to portal hypertension:

 • Secondary bacterial peritonitis

 • TB peritonitis

 • Peritoneal carcinomatosis (+cytology)

 • Chylous ascites (triglycerides >200)

 • Hypoalbuminemia (malnutrition, nephrotic syndrome)

 • Serositis (e.g. SLE)

 • Pancreaticobiliary



#SAAG #Paracentesis #Fluid #Interpretation #Laboratory #Ascites #diagnosis #differential #hepatology