What is the initial management of acute ascites?

Initial Management of Acute Ascites

The initial management of acute ascites must include a diagnostic paracentesis with appropriate ascitic fluid analysis to determine the underlying cause before initiating any treatment. 1

Diagnostic Approach

Step 1: Diagnostic Paracentesis

• Mandatory for all patients with new-onset ascites that is accessible for sampling 1
• Should be performed before initiating any therapy 1
• Typical site: 15 cm lateral to the umbilicus in the left or right lower quadrant 1
• Complications are rare (<1% for abdominal hematomas, <0.1% for serious complications) 1
• Paracentesis is not contraindicated in patients with abnormal coagulation profiles 1

Step 2: Essential Ascitic Fluid Analysis

1. Serum-ascites albumin gradient (SAAG):

   • Calculate by subtracting ascitic fluid albumin from serum albumin
   • SAAG ≥1.1 g/dL indicates portal hypertension with 97% accuracy 1
   • Helps differentiate between portal hypertension-related and non-portal hypertension-related ascites

2. Ascitic fluid neutrophil count:

   • To rule out spontaneous bacterial peritonitis (SBP)
   • SBP diagnosis: neutrophil count >250/mm³ 1

3. Ascitic fluid total protein:

   • Low protein (<15 g/L) indicates increased risk of SBP 1

4. Ascitic fluid culture:

   • Bedside inoculation into blood culture bottles when infection is suspected 1

Step 3: Additional Testing Based on Clinical Suspicion

• Cytology: if malignancy is suspected
• Amylase: if pancreatic disease is suspected
• Adenosine deaminase: if tuberculosis is suspected
• Other tests based on pre-test probability of specific diagnoses 1

Treatment Approach for Cirrhotic Ascites

Once diagnostic paracentesis confirms cirrhosis as the cause (75% of cases in Western countries) 1:

Step 1: Classify Ascites Severity

• Grade 1 (mild): Only detectable by ultrasound
• Grade 2 (moderate): Moderate symmetric abdominal distension
• Grade 3 (large): Marked abdominal distension 1

Step 2: Initiate Treatment Based on Severity

For Grade 1 Ascites:

• Sodium restriction alone (2 g or 90 mmol/day) 1

For Grade 2 Ascites:

1. Dietary sodium restriction:

   • Moderate restriction to 2 g (90 mmol) sodium/day 1
   • Patient education is essential for adherence 1
   • Consider dietician consultation 1

2. Diuretic therapy:

   • First-line: Aldosterone antagonist (spironolactone)

     • Starting dose: 100 mg/day 1
     • Can be increased progressively up to 400 mg/day 1
     • Allow at least 72 hours between dose adjustments due to long half-life 1
     • Mechanism: Antagonizes aldosterone, causing sodium excretion while retaining potassium 2

   • Add if needed: Loop diuretic (furosemide)

     • Starting dose: 40 mg/day 1
     • Can be increased progressively up to 160 mg/day 1
     • Caution in hepatic cirrhosis as sudden fluid/electrolyte changes may precipitate hepatic coma 3

3. Monitor response:

   • "Spot" urine sodium/potassium ratio >1 indicates adequate natriuresis 1
   • If ratio ≤1, increase diuretics 1
   • Monitor for complications: hyponatremia, hypokalemia, hypomagnesemia, renal impairment 2

For Grade 3 (Large) Ascites:

• Large volume paracentesis followed by albumin infusion
• Then maintenance therapy with sodium restriction and diuretics as above 1

Special Considerations

Spontaneous Bacterial Peritonitis (SBP)

• If neutrophil count >250/mm³, initiate empiric antibiotic therapy immediately 1
• Choice of antibiotic should consider local resistance patterns 1

Refractory Ascites

• Defined as ascites that cannot be mobilized despite sodium restriction and maximum diuretic therapy (spironolactone 400 mg/day and furosemide 160 mg/day) 4
• Management options include:
  • Repeated large-volume paracentesis with albumin
  • Transjugular intrahepatic portosystemic shunt (TIPS)
  • Liver transplantation evaluation 5, 6

Monitoring

• Serum electrolytes, renal function within 1 week of initiating or adjusting diuretic therapy 2
• More frequent monitoring for patients with impaired renal function or taking other medications that may cause hyperkalemia 2
• Weight monitoring to assess fluid loss
• Reassess ascites severity regularly

Common Pitfalls to Avoid

• Assuming cirrhosis is the cause without diagnostic paracentesis
• Initiating diuretics before ruling out SBP
• Rapid diuresis leading to electrolyte abnormalities or hepatic encephalopathy
• Inadequate monitoring of renal function and electrolytes
• Failure to consider liver transplantation evaluation for patients with ascites 7