Diagnosis
- Imaging:
- Initial: Abdominal Ultrasound (detects as little as 100 mL of fluid, evaluates liver parenchymal echogenicity, screens for portal vein thrombosis).
- Gold Standard/Confirmatory Procedure:
- Diagnostic Paracentesis (indicated for all patients with new-onset ascites or suspected infection/SBP).
- Key Labs (Ascitic Fluid Analysis):
- Serum-Ascites Albumin Gradient (SAAG): Serum albumin minus ascitic fluid albumin.
- SAAG ≥ 1.1 g/dL (indicates portal HTN): Cirrhosis, HF, Budd-Chiari syndrome, portal vein thrombosis.
- SAAG < 1.1 g/dL (indicates non-portal HTN): Peritoneal carcinomatosis, TB peritonitis, nephrotic syndrome, pancreatitis.
- Ascitic Fluid Total Protein:
- < 2.5 g/dL: Cirrhosis, nephrotic syndrome.
- ≥ 2.5 g/dL: Cardiac ascites (HF), Budd-Chiari, TB peritonitis.
- Cell Count & Differential: PMN count ≥ 250/mm³ is diagnostic for Spontaneous Bacterial Peritonitis (SBP).
- Other tests: Cytology (malignancy), Amylase (pancreatic ascites), Acid-fast bacilli stain/culture (TB).