What is the management approach for patients with low Serum-Ascites Albumin Gradient (SAAG) ascites?

Management of Low SAAG Ascites

The management of patients with low Serum-Ascites Albumin Gradient (SAAG) ascites should focus on identifying and treating the underlying cause, as these patients typically do not respond to salt restriction and diuretics (with the exception of nephrotic syndrome). 1

Diagnostic Approach

• Initial laboratory investigation of ascitic fluid should include cell count with differential, total protein, and SAAG calculation 1
• A SAAG <1.1 g/dL indicates non-portal hypertension causes of ascites with approximately 97% accuracy 1, 2
• Common causes of low SAAG ascites include:
  • Peritoneal carcinomatosis/malignancy 1, 3
  • Tuberculous peritonitis 1, 2
  • Nephrotic syndrome 1, 4
  • Pancreatic ascites 1, 5
• If ascitic fluid infection is suspected, fluid should be cultured at bedside in blood culture bottles prior to antibiotic initiation 1
• Additional testing should be ordered based on clinical suspicion:
  • Cytology for suspected malignancy 1
  • Carcinoembryonic antigen and alkaline phosphatase for suspected gut perforation 1
  • Tuberculosis testing when clinically indicated 1, 2

Treatment Strategy

• Unlike high SAAG ascites (≥1.1 g/dL), patients with low SAAG ascites generally do not respond to sodium restriction and diuretics 1
• Treatment must target the underlying disorder causing the ascites 1
• For nephrotic syndrome (the exception), management may include:
  • Treatment of the underlying kidney disease 4
  • Possible response to diuretics when hypoalbuminemia is the predominant factor 4
• For malignancy-related ascites:
  • Treatment of the underlying malignancy 3
  • Palliative paracentesis may be required for symptom relief 3
• For tuberculous peritonitis:
  • Anti-tuberculosis therapy 2, 6

Important Clinical Considerations

• In patients with known cirrhosis who unexpectedly have a low SAAG, consider repeat paracentesis, as studies show 73% will convert to high SAAG on repeat testing 5
• Low SAAG ascites evaluation has higher diagnostic yield in patients without cirrhosis (75% identifiable cause) compared to those with cirrhosis (38% identifiable cause) 5
• Rare cases of heart failure can present with low SAAG ascites, requiring additional imaging studies like triphasic abdominal CT to confirm diagnosis 7
• Total protein concentration in ascitic fluid should be measured to evaluate risk of spontaneous bacterial peritonitis (higher risk when proteins <1.5 g/dL) 1, 4

Follow-up Recommendations

• Patients with unexplained low SAAG ascites should undergo comprehensive evaluation to identify the underlying cause 6
• If initial evaluation is inconclusive, consider repeat paracentesis, especially in patients with known cirrhosis 5
• Monitor for response to treatment of the underlying condition 1
• Consider liver transplantation evaluation for patients with cirrhosis and ascites, as development of ascites indicates poor prognosis 1