Ascitic Fluid analysis in cirrhosis

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                 Ascitic Fluid analysis in cirrhosis




When performing an ascitic tap in a patient with cirrhosis, the following tests should be prioritized, along with their clinical rationales:

1. Cell Count and Differential

  • Purpose:

    • Neutrophil count is critical to diagnose spontaneous bacterial peritonitis (SBP). A neutrophil count >250 cells/mm³ confirms SBP, necessitating immediate antibiotic therapy.

    • Total white blood cell count may also support infection detection.

  • Explanation: SBP is a common and life-threatening complication in cirrhotic ascites. Early diagnosis improves outcomes.

2. Ascitic Fluid Culture

  • Purpose: Identifies the causative organism in SBP.

  • Method: Inoculate 10–20 mL of ascitic fluid into aerobic and anaerobic blood culture bottles at the bedside.

  • Explanation: Bedside inoculation increases bacterial yield (sensitivity ~50-70% in SBP). Guides targeted antibiotic therapy, especially in culture-positive cases.

3. Serum-Ascites Albumin Gradient (SAAG)

  • Purpose:

    • Calculated as serum albumin – ascitic fluid albumin (measured on the same day).

    • SAAG ≥1.1 g/dL confirms portal hypertension as the cause of ascites (e.g., cirrhosis).

    • SAAG <1.1 g/dL suggests non-portal hypertensive causes (e.g., malignancy, tuberculosis).

  • Explanation: Validates the underlying pathophysiology, even in known cirrhotics, to rule out mixed or alternative etiologies.

4. Ascitic Fluid Total Protein

  • Purpose:

    • Protein <2.5 g/dL supports portal hypertension.

    • Protein <1.5 g/dL indicates higher SBP risk, warranting prophylactic antibiotics (e.g., norfloxacin).

  • Explanation: Low protein levels correlate with reduced ascitic fluid opsonic activity, increasing infection susceptibility.


  • SAAG and total protein help classify ascites:

    • High SAAG + low protein: Portal hypertension (cirrhosis, heart failure).

    • Low SAAG + high protein: Exudative causes (malignancy, TB).


Additional Tests (Context-Dependent)

  • Glucose and Lactate Dehydrogenase (LDH):

    • Differentiate SBP (normal glucose, mildly elevated LDH) from secondary peritonitis (e.g., gut perforation: very low glucose, high LDH).

  • Amylase:

    • Elevated levels suggest pancreatic ascites (e.g., pancreatic duct leak).

  • Gram Stain:

    • Low sensitivity in SBP but may rapidly identify organisms in severe infections.

  • Cytology:

    • Ordered if malignancy is suspected (e.g., peritoneal carcinomatosis).

  • Bilirubin/Creatinine:

    • Bilirubin (ascitic fluid > serum) suggests biliary leak.

    • Creatinine (ascitic fluid > serum) indicates urinary tract injury (e.g., bladder rupture).


Key Considerations

  • Empirical Antibiotics: Start immediately if SBP is suspected (neutrophils >250 cells/mm³) while awaiting culture results.

  • Secondary Peritonitis: Suspect if ascitic fluid shows multiple organisms, very high LDH, or low glucose. Imaging (e.g., CT) is critical here.

  • Prophylaxis: Patients with ascitic protein <1.5 g/dL or prior SBP benefit from long-term antibiotic prophylaxis.

By systematically evaluating these tests, you can diagnose complications of cirrhotic ascites and guide evidence-based management.

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