What is the appropriate management and treatment approach for a patient presenting with peritoneal fluid accumulation, considering potential underlying causes such as liver cirrhosis, heart failure, or cancer?

Management of Peritoneal Fluid (Ascites)

Perform diagnostic paracentesis immediately on all patients with new-onset ascites to determine the underlying cause, as this is the most rapid and cost-effective diagnostic approach. 1

Initial Diagnostic Workup

Essential first-line tests on ascitic fluid include:

• Cell count with differential to detect infection (polymorphonuclear leukocyte count >250 cells/mm³ indicates spontaneous bacterial peritonitis) 1
• Ascitic fluid albumin and serum albumin to calculate the serum-ascites albumin gradient (SAAG) 1, 2, 3
• Ascitic fluid total protein concentration 1
• If infection is suspected, inoculate ascitic fluid into blood culture bottles at the bedside before starting antibiotics (this increases culture yield from 50% to 80%) 1

SAAG interpretation determines treatment approach:

• SAAG ≥1.1 g/dL indicates portal hypertension with 97% accuracy (cirrhosis, heart failure, portal vein thrombosis) 1, 2, 3
• SAAG <1.1 g/dL indicates non-portal hypertensive causes (peritoneal carcinomatosis, tuberculosis, nephrotic syndrome) 1, 3

Determining the Underlying Cause

Cirrhosis accounts for approximately 85% of ascites cases in Western populations, while 15% have non-hepatic causes including cancer, heart failure, tuberculosis, or nephrotic syndrome. 1

Additional testing based on clinical suspicion:

• Cytology: Order only when peritoneal carcinomatosis is suspected (history of breast, colon, gastric, or pancreatic cancer); sensitivity is 96.7% if three 50 mL samples are sent fresh and processed immediately 1
• Mycobacterial testing: Order only in high-risk patients (recent immigration from endemic areas, HIV/AIDS); ascitic fluid adenosine deaminase (ADA) >32 U/L has 91.7% sensitivity and 92% specificity for tuberculous peritonitis in cirrhotic patients 1
• Secondary peritonitis markers: If perforated viscus suspected, measure ascitic glucose (<50 mg/dL), LDH (higher than serum), CEA (>5 ng/mL), or alkaline phosphatase (>240 U/L) 1

Critical pitfall: Never order serum CA125 in patients with ascites—it is elevated in all patients with ascites regardless of cause and may lead to unnecessary gynecologic surgery, particularly in women with cirrhosis. 1

Treatment for Portal Hypertensive Ascites (SAAG ≥1.1 g/dL)

First-Line Medical Management

Sodium restriction to 2000 mg/day (88 mmol/day) combined with diuretic therapy is the cornerstone of treatment. 2

Diuretic regimen:

• Start spironolactone 100 mg once daily plus furosemide 40 mg once daily 2, 4
• Maximum doses: spironolactone 400 mg/day and furosemide 160 mg/day 2, 4
• In cirrhotic patients, initiate therapy in hospital setting and titrate slowly due to risk of hepatic encephalopathy 4, 5

Monitoring parameters:

• Daily weight at same time each day (after voiding) 2
• Target weight loss: 0.5 kg/day without peripheral edema, or 1 kg/day with peripheral edema 2
• Exceeding these targets risks plasma volume contraction, renal failure, and hyponatremia 2
• Monitor serum electrolytes and creatinine regularly, especially during first weeks of therapy 2

Assessing diuretic response:

• If weight loss inadequate, check 24-hour urinary sodium excretion (target >78 mmol/day) 2
• Alternatively, spot urine sodium-to-potassium ratio >1 correlates with adequate sodium excretion with 90% accuracy 2
• Lack of weight loss despite adequate urinary sodium indicates dietary non-compliance 2

Management of Tense Ascites

For patients with tense, uncomfortable ascites, perform large-volume paracentesis (LVP) for immediate symptom relief, then resume diuretics to prevent reaccumulation. 2

Post-paracentesis albumin administration:

• Give intravenous albumin 8 g per liter of ascitic fluid removed when >5 liters removed 1, 2
• This prevents post-paracentesis circulatory dysfunction, which increases mortality 1
• Administer albumin slowly to avoid cardiac overload in patients with underlying cardiomyopathy 1

Treatment of Underlying Liver Disease

Addressing the underlying cause is critical for ascites control and survival:

• Alcohol-related cirrhosis: Abstinence is essential; Child-Pugh class C patients who stop drinking have 75% 3-year survival versus 0% in those who continue 2
• Hepatitis B cirrhosis: Antiviral treatment can lead to dramatic improvement even in decompensated disease 2
• For irreversible liver disease, refer for liver transplantation evaluation, as development of ascites reduces 5-year survival from 80% to 30% 6

Management of Spontaneous Bacterial Peritonitis

If PMN count ≥250 cells/mm³, administer intravenous albumin 1.5 g/kg on day 1 and 1 g/kg on day 3 in addition to antibiotics. 1

• This combination reduces renal impairment (10% vs 33%) and mortality (22% vs 41%) compared to antibiotics alone 1

Critical Medication Precautions

Avoid medications that worsen ascites or precipitate complications:

• NSAIDs: Reduce urinary sodium excretion and can convert diuretic-sensitive patients to refractory 2
• ACE inhibitors: Worsen hypotension in cirrhotic patients 2
• Fluid restriction: Generally unnecessary unless serum sodium <120-125 mmol/L 2

Recognition of Mixed Ascites

Approximately 5% of patients have two or more causes of ascites (e.g., cirrhosis plus peritoneal carcinomatosis, heart failure plus diabetic nephropathy plus cirrhosis). 1

• In these patients, each individual factor may not be severe enough alone to cause fluid retention, but the sum of predisposing factors leads to sodium and water retention 1
• All underlying causes must be addressed for effective treatment 2

When to Consider Refractory Ascites

Refractory ascites is defined as unresponsive to sodium restriction and high-dose diuretics (spironolactone 400 mg/day plus furosemide 160 mg/day). 2

Management options include:

• Serial therapeutic paracenteses with albumin replacement 2
• Transjugular intrahepatic portosystemic shunt (TIPS) in selected patients 2
• Liver transplantation evaluation should be prioritized 2, 6