Overview

• Abnormal accumulation of fluid within the peritoneal cavity
• Causes of ascites can be grouped into those with a serum-ascites albumin gradient (SAAG) of >11g/L (portal hypertension) or <11g/L (all other causes)
• SAAG = [Serum Albumin] - [Ascites Albumin)

Aetiology:

• SAAG >11g/L ⇒ ascitic fluid is transudative (low protein)

  • Portal Hypertension, cirrhosis, congestive heart failure, budd-chiari syndrome, alcohol-related liver disease, liver failure
    • Portal Hypertension

• SAAG <11g/L ⇒ ascitic fluid is exudative (high protein)

  • Hypoalbuminemia → may be due to nephrotic syndrome or severe malnutrition
  • Intra-abdominal Malignancy with peritoneal spread
  • Infections → eg. tuberculosis
  • Pancreatitis

  MIPN = malignancy, infection, pancreatitis, nephrotic syndrome

  • Pleural Tap and SAAG Interpretation

Making Diagnosis

Clinical Features:

• Progressive Abdominal Distension → associated symptoms include early satiety, weight gain, dyspnoea
• Shifting Dullness → change from dull to resonant when patient changes from supine to lateral decubitus position
• Signs of Underlying Disease → Chronic Liver Disease (jaundice, spider naevi, palmer erythema), HF (elevated JVP), Upper Abdominal Malignancy (virchow’s node and weight loss)

Investigations:

• Abdominal Ultrasound → inital study of choice if suspicion of new-onset ascites
• Ascitic Fluid Analysis → appearance can provide evidence of underlying cause
• Diagnostic Paracentesis → to detect any peritoneal infections