How is portal hypertension diagnosed on ultrasound?

Diagnosing Portal Hypertension on Ultrasound

The most reliable ultrasound findings for diagnosing portal hypertension are the presence of portosystemic collaterals, which are 100% specific for clinically significant portal hypertension (CSPH). 1

Key Ultrasound Findings for Portal Hypertension Diagnosis

Direct Signs (Highly Specific)

• Portosystemic collaterals: The presence of portocollateral circulation (recanalized paraumbilical vein, spontaneous splenorenal circulation, dilated left and short gastric veins) is 100% specific for CSPH 1
• Flow reversal: Finding reversal of flow within the portal system is 100% specific for CSPH 1
• Patent or enlarged paraumbilical vein: Present in 85.6% of patients with portal hypertension, making it a sensitive indicator 2

Indirect Signs (Supportive)

• Splenomegaly: While sensitive for portal hypertension, it's nonspecific when used alone but valuable when combined with other parameters 1
• Portal vein diameter: Dilatation (>13mm) has only 41.1% sensitivity for portal hypertension 2, 3
• Reduced portal vein velocity: Can be measured with Doppler but shows high variability 1, 2
• Congestion index of portal vein: Combination of portal vein diameter and velocity 1

Diagnostic Algorithm for Portal Hypertension on Ultrasound

1. First-line assessment: Look for portosystemic collaterals and flow reversal in portal system 1

   • If present → CSPH confirmed (100% specificity)
   • If absent → Continue evaluation

2. Second-line assessment: Evaluate for paraumbilical vein patency/enlargement 2

   • If present → High likelihood of portal hypertension (85.6% sensitivity)
   • If absent → Continue evaluation

3. Third-line assessment: Measure spleen size and portal vein parameters 1

   • Splenomegaly + portal vein diameter >13mm + reduced portal flow velocity → Suggestive of portal hypertension
   • Normal findings → Portal hypertension less likely but not excluded

Advanced Assessment Methods

Elastography Techniques

• Liver stiffness measurement (LSM) by transient elastography (TE):

  • Cut-off of >20-25 kPa should be used to diagnose CSPH in patients with compensated advanced chronic liver disease (cACLD) 1
  • Has excellent diagnostic accuracy with AUROC of 0.93 1

• Combined parameters improve accuracy:

  • LSPS score (liver stiffness × spleen size/platelet count):

    • 2.06 has 90% specificity for diagnosing CSPH 1

  • Platelet count and spleen size should be used with LSM to improve risk stratification 1

Limitations and Pitfalls

• Obesity: Limits conventional ultrasound assessment due to poor penetration 1
• Steatosis: Can create a "fatty-fibrotic" pattern that overlaps with cirrhosis appearance 1
• Etiology considerations: Most data on elastography cutoffs are from viral and alcoholic cirrhosis; other etiologies may have different thresholds 1
• Acute inflammation: Can falsely elevate liver stiffness measurements 1

Clinical Correlation

• While ultrasound findings are valuable, they should be interpreted alongside:

  • Laboratory parameters (platelet count, Child-Pugh score) 1
  • Clinical signs of portal hypertension (spider nevi, visible abdominal collaterals) 1

• For definitive assessment: Hepatic venous pressure gradient (HVPG) remains the gold standard for measuring portal pressure (CSPH defined as HVPG ≥10 mmHg) 1, 4

Emerging Techniques

• EUS-guided portal pressure gradient (EUS-PPG) measurement: Allows direct measurement of portal pressure during endoscopy 1
• Multiparametric MRI: Shows promising results for predicting CSPH but requires further validation 1
• Radiomics approaches: Being developed to stage liver fibrosis based on ultrasound images but not yet ready for clinical implementation 1