How to assess portal hypertension?

How to Assess Portal Hypertension

Hepatic venous pressure gradient (HVPG) measurement via hepatic vein catheterization remains the gold standard for diagnosing and quantifying portal hypertension, but when this invasive test is not feasible, use ultrasound with Doppler as first-line imaging followed by transient elastography with liver stiffness measurement (LSM) for risk stratification. 1, 2

Invasive Assessment: The Reference Standard

HVPG measurement is the single best predictor of outcome available to clinicians and should be used when precise quantification is needed for prognostication or monitoring therapeutic response. 3, 2

HVPG Diagnostic Thresholds:

• Portal hypertension present: HVPG >5 mm Hg 3, 2
• Clinically significant portal hypertension (CSPH): HVPG ≥10 mm Hg—this threshold predicts risk of clinical decompensation and development of varices 3, 1
• High mortality risk: HVPG ≥16 mm Hg—strongly associated with death in both compensated and decompensated cirrhosis 3, 2
• Acute bleeding risk: HVPG ≥20 mm Hg—predicts failure to control bleeding and early rebleeding 2

Important Limitation:

HVPG is normal in prehepatic and presinusoidal portal hypertension, so it only accurately measures sinusoidal and postsinusoidal causes. 2 This invasive test is limited by availability, technical requirements, and is impractical for routine screening. 1

Noninvasive Assessment: Practical Clinical Approach

First-Line: Ultrasound with Doppler

Use abdominal ultrasound with Doppler as the initial noninvasive approach—it is safe, inexpensive, and provides morphological evidence of portal hypertension. 1, 2

Look for these 100% specific findings for CSPH:

• Portosystemic collaterals (recanalized umbilical vein, splenorenal shunts, gastric varices) 1, 4
• Portal vein flow reversal (hepatofugal flow) 1, 4

If these direct signs are present, CSPH is confirmed without need for further testing. 4

Additional Ultrasound Parameters (when direct signs absent):

• Splenomegaly: Sensitive but nonspecific alone; valuable when combined with other parameters 1, 4
• Portal vein velocity: Can be measured with Doppler but shows high variability 4
• Congestion index: Combination of portal vein diameter and velocity 4

Second-Line: Transient Elastography (Liver Stiffness Measurement)

When ultrasound does not show direct signs of CSPH, transient elastography with LSM is the best available noninvasive test for detecting CSPH. 3, 1

Use this LSM algorithm for risk stratification:

• LSM ≤15 kPa: CSPH is highly unlikely (sensitivity 90-96%) 3, 1
• LSM 15-25 kPa: Intermediate zone requiring additional assessment 1
• LSM ≥25 kPa: CSPH is likely present (specificity 82-93%) 3, 1

The European Association for the Study of the Liver recommends an LSM cutoff of >20-25 kPa to diagnose CSPH in compensated advanced chronic liver disease. 1, 4

Blood-Based Tests: Limited Utility

Do not use blood-based tests alone to diagnose portal hypertension—they have poor accuracy and should only serve as adjunctive information. 1

Performance of Common Blood Tests:

• Platelet count <100,000/mcL: Only 78% sensitivity with specificity <50% 1
• APRI score: 56% sensitivity and 68% specificity for CSPH 3, 1
• FIB-4 score: 54% sensitivity and 73% specificity for CSPH 3, 1

Combined Scoring Systems: Enhanced Accuracy

The Liver stiffness-spleen diameter to platelet ratio score (LSPS) improves diagnostic accuracy when combining parameters: 1

• LSPS >2.06: 90% specificity for CSPH 1, 4
• LSPS 0.927 kPa: 99% sensitivity, 54% specificity 1
• LSPS 3.75 kPa: 52% sensitivity, 97% specificity 1

Practical Clinical Algorithm

1. Start with ultrasound with Doppler looking for portosystemic collaterals or flow reversal 1, 4

   • If present → CSPH confirmed (100% specific)
   • If absent → Proceed to step 2

2. Perform transient elastography (LSM) 1

   • LSM ≤15 kPa → CSPH unlikely, consider alternative diagnoses
   • LSM 15-25 kPa → Consider HVPG measurement or combined scoring (LSPS)
   • LSM ≥25 kPa → CSPH likely, proceed with management

3. Consider HVPG measurement when: 2

   • Noninvasive tests are equivocal
   • Precise quantification needed for prognostication
   • Monitoring therapeutic response required
   • Suspected prehepatic or presinusoidal causes

Critical Pitfalls to Avoid

• Do not rely on platelet count alone to diagnose or exclude CSPH—it lacks sufficient accuracy 2
• Remember that HVPG is normal in prehepatic and presinusoidal portal hypertension—consider alternative diagnostic methods in these cases 2
• Do not interpret splenomegaly alone as diagnostic—it is nonspecific and must be combined with other parameters 2
• Recognize substantial heterogeneity in LSM cutoffs across different liver disease etiologies—most data derived from HCV patients 3
• Understand that esophageal varices are an imprecise measure of portal hypertension—not all patients with CSPH develop varices, and varix size assessment is subjective 3