Etiology

The etiology can be determined using the serum-ascites albumin gradient (SAAG) based on Starling's law.

SAAG = (albumin levels in serum) - (albumin levels in ascitic fluid)

Portal hypertension

• Presinusoidal

  • Splenic or portal vein thrombosis

  • Schistosomiasis

• Sinusoidal

  • Hepatic (common)

    • Cirrhosis

    • Alcohol-related liver disease

    • Liver metastases

• Postsinusoidal

  • Cardiac

    • Right heart failure

    • Constrictive pericarditis

  • Budd-Chiari syndrome

Arterial vasodilation hypothesis in cirrhosis :

• Portal hypertension → vasodilation → reduced systemic vascular resistance and reduced mean arterial blood pressure

• Activation of endogenous vasoconstrictors, renal sodium and water retention, and renal vasoconstriction → hyperdynamic circulation

Right-sided heart failure: backflow of blood obstructing the venous outflow of the liver

Budd-Chiari syndrome: congestion of the portal/hepatic collateral veins and hypertrophy of the caudate lobe of the liver → compression of the sinusoids and intrahepatic inferior vena cava

All result in ↑ pressure in portal vein → ↑ hydrostatic pressure in the hepatic vessels → pushing of fluid out from the intravascular space to the peritoneal cavity

Hypoalbuminemia

• Nephrotic syndrome

• Severe malnutrition

• Protein-losing enteropathy

Malignancy

Infections (e.g., tbc)

Pancreatitis