Ascites - Medical Lecture Notes

 

Ascites - Medical Lecture Notes

Definition

Ascites is the pathological accumulation of fluid in the peritoneal cavity, most commonly due to portal hypertension caused by liver cirrhosis. It is a key sign of advanced liver disease, though other causes must be considered.

Pathophysiology

• Portal Hypertension: Increased hydrostatic pressure due to cirrhosis causes fluid leakage into the peritoneal space.
• Hypoalbuminemia: Reduced plasma oncotic pressure from impaired hepatic albumin synthesis allows fluid to leak out of capillaries.
• Splanchnic Vasodilation: Nitric oxide release causes vasodilation, further reducing effective circulating volume.
• RAAS Activation: Sodium and water retention worsens fluid accumulation.

Common Causes of Ascites

• Cirrhosis (≈ 80% of cases)
• Malignancy (Peritoneal carcinomatosis, lymphomas)
• Infectious: Tuberculosis peritonitis
• Nephrotic syndrome
• Congestive heart failure
• Pancreatitis
• Chylous ascites (lymphatic obstruction)

Clinical Presentation

• Progressive abdominal distension
• Early satiety
• Shortness of breath (due to diaphragmatic pressure)
• Shifting dullness, fluid thrill
• Peripheral edema (if hypoalbuminemia is present)

Diagnostic Work-up

1. History & Physical Examination
2. Ultrasound Abdomen: Most sensitive for small amounts of fluid (>100 ml)
3. Diagnostic Paracentesis: Always performed in new-onset ascites, suspected infection or deterioration.

Ascitic Fluid Analysis

• Appearance: Clear (transudate), cloudy/purulent (infection), bloody (malignancy/TB)
• Serum Ascites Albumin Gradient (SAAG):
  • SAAG ≥1.1 g/dL → suggests portal hypertension (cirrhosis, CHF)
  • SAAG <1.1 g/dL → suggests non-portal hypertensive causes (TB, cancer, pancreatitis)
• Cell count & differential: Neutrophils >250/mm³ suggest spontaneous bacterial peritonitis (SBP)
• Culture, glucose, LDH, cytology, AFB if TB suspected

Types of Ascites

1. Transudative Ascites – Low protein content (e.g., cirrhosis, nephrotic syndrome)
2. Exudative Ascites – High protein content (e.g., TB, malignancy, pancreatitis)
3. Hemorrhagic Ascites – Bloody ascitic fluid (e.g., trauma, malignancy)
4. Chylous Ascites – Milky appearance due to lymph (e.g., lymphoma, TB, filariasis)

Complications

• Spontaneous Bacterial Peritonitis (SBP): Life-threatening infection of ascitic fluid
• Hepatorenal Syndrome (HRS)
• Respiratory compromise
• Malnutrition and sarcopenia

Management

1. General Measures: Salt restriction (<2g/day), fluid restriction if hyponatremic
2. Diuretics:
   • Spironolactone (first-line)
   • Furosemide added if needed (typical ratio 100:40 mg)
3. Therapeutic Paracentesis: For tense ascites; replace albumin if large volume removed
4. SBP Treatment: Empirical IV cefotaxime; prophylactic norfloxacin in high-risk cases
5. Refractory Ascites: TIPS (Transjugular Intrahepatic Portosystemic Shunt)
6. Definitive treatment: Liver transplant

Prognosis

Ascites indicates decompensated liver disease. Median survival is approximately 2 years without transplant, especially if refractory or complicated by SBP or hepatorenal syndrome.

Important Clinical Points

• Always analyze ascitic fluid when new or worsening ascites appears.
• Monitor renal function and electrolytes frequently during diuretic therapy.
• SBP can be asymptomatic; always have a high index of suspicion.

References & Resources

• Harrison's Principles of Internal Medicine
• Davidson's Principles and Practice of Medicine
• Oxford Handbook of Clinical Medicine
• Uptodate: Evaluation of ascites in adults
• American Association for the Study of Liver Diseases (AASLD) Guidelines

Created for medical education. For any personal health concerns, consult a licensed physician.