How do I diagnose and treat a patient with ascites?

Diagnosis and Management of Ascites

Immediate Diagnostic Steps

Perform a diagnostic paracentesis immediately in all patients with new-onset ascites or worsening abdominal fluid accumulation—this is the single most important diagnostic and potentially life-saving intervention. 1, 2, 3

Physical Examination Findings

• Test for shifting dullness by percussing the flanks with the patient supine; this has 83% sensitivity and requires at least 1,500 mL of fluid to be detectable 1, 3
• Check for jugular venous distension, which indicates cardiac ascites rather than cirrhotic ascites 1, 4
• In obese patients, physical examination is unreliable—obtain an abdominal ultrasound for confirmation 1, 3

Essential Paracentesis Technique

• Perform the tap 15 cm lateral to the umbilicus in the lower quadrants to avoid epigastric vessels 2
• Do not withhold paracentesis for coagulopathy or thrombocytopenia—serious complications occur in less than 1 in 1,000 procedures 2, 3, 4
• Inoculate at least 10 mL of ascitic fluid into aerobic and anaerobic blood culture bottles at bedside before any antibiotics are given 1, 2

Critical Laboratory Analysis

Send ascitic fluid for:

• Neutrophil count: >250 cells/mm³ diagnoses spontaneous bacterial peritonitis (SBP) requiring immediate antibiotics 1, 2, 3
• Total protein and albumin: Obtain simultaneous serum albumin to calculate the serum-ascites albumin gradient (SAAG) 1, 2, 3
• SAAG ≥1.1 g/dL (or 11 g/L) indicates portal hypertension with 97% accuracy—this is the key diagnostic calculation 1, 3, 4
• Total protein <1.5 g/dL identifies patients at high risk for developing SBP 1

Determine the Underlying Cause

Cirrhosis accounts for 75-85% of ascites cases in Western countries, but always investigate other causes 1, 3

Key History Elements

• Alcohol use, viral hepatitis risk factors, and lifetime maximum body weight (nonalcoholic steatohepatitis is often causative in patients without obvious risk factors) 1, 4
• Past history of cancer, heart failure, renal disease, tuberculosis, or pancreatitis 1, 4

Additional Testing Based on SAAG

• SAAG ≥1.1 g/dL: Portal hypertension (cirrhosis, alcoholic hepatitis, heart failure, Budd-Chiari syndrome) 1, 3
• SAAG <1.1 g/dL: Non-portal hypertensive causes (peritoneal carcinomatosis, tuberculosis, pancreatic ascites, nephrotic syndrome) 1

Immediate Treatment for Cirrhotic Ascites

For Tense/Gross Ascites (Grade 3)

Perform therapeutic paracentesis as first-line treatment, removing all accessible fluid in a single session. 2

• Administer albumin at 8 g per liter of ascites removed when removing >5 liters to prevent post-paracentesis circulatory dysfunction 2
• This provides immediate symptom relief and allows for subsequent diuretic therapy 2

Dietary Sodium Restriction

• Restrict dietary sodium to 2 g/day immediately and provide formal dietician consultation 2
• Do not restrict fluids unless serum sodium <125 mmol/L 2

Diuretic Therapy

Start combination therapy with spironolactone 100 mg daily plus furosemide 40 mg daily—patients with long-standing ascites respond better to combined treatment than monotherapy. 2

• Never use furosemide as monotherapy, as it is less effective than spironolactone in portal hypertension 2
• Increase spironolactone stepwise up to 400 mg/day, waiting at least 72 hours between increases due to its long half-life 2
• Maximum doses: spironolactone 400 mg/day plus furosemide 160 mg/day 2

Critical Monitoring Parameters

• Check serum potassium within 1 week of initiation or dose changes, then regularly 2
• Monitor serum creatinine, electrolytes, and renal function frequently during diuresis 2
• If creatinine rises significantly or exceeds 150 μmol/L, stop diuretics immediately 2
• For serum sodium <120 mmol/L, stop diuretics and consider volume expansion with albumin 2

Treatment of Underlying Liver Disease

Treating the underlying cause of cirrhosis is fundamental to controlling ascites. 1

• Alcohol abstinence improves liver fibrosis, lowers portal pressure, and increases survival in alcoholic cirrhosis 1
• Oral antiviral agents for hepatitis B improve liver function and reduce ascites 1
• Direct-acting antivirals for hepatitis C (e.g., sofosbuvir/velpatasvir) improve MELD and Child-Pugh scores in patients with cirrhosis and ascites 1

Management of Refractory Ascites

Ascites is refractory when it cannot be mobilized or recurs ≥3 times within 12 months despite sodium restriction and maximum diuretics (spironolactone 400 mg/day plus furosemide 160 mg/day). 2, 4

Options include:

• Repeated large-volume paracentesis with albumin replacement 2, 4
• Transjugular intrahepatic portosystemic shunt (TIPS) in selected patients 4

Liver Transplantation Referral

Refer all patients with ascites for liver transplantation evaluation immediately—the development of ascites reduces 5-year survival from 80% in compensated cirrhosis to 30% in decompensated cirrhosis. 1, 2, 3

Critical Pitfalls to Avoid

• Never assume alcoholic patients have alcoholic liver disease—always investigate other causes 2, 4
• Avoid NSAIDs, which reduce diuretic efficacy and worsen renal function 2
• Do not give fresh frozen plasma before paracentesis—it is not supported by evidence and complications are rare 2, 4
• Never miss SBP—perform paracentesis promptly in any hospitalized patient with ascites, even without symptoms of infection 1
• Do not initiate diuretics in hepatic coma or severe electrolyte depletion until the basic condition is improved, as sudden fluid shifts can precipitate hepatic coma 5