How do you diagnose systemic portal hypertension?

How to Test for Portal Hypertension

Hepatic venous pressure gradient (HVPG) measurement via hepatic vein catheterization is the gold standard for diagnosing portal hypertension, but in clinical practice, start with ultrasound with Doppler to look for direct signs (portosystemic collaterals or flow reversal), and if absent, use transient elastography with liver stiffness measurement as the best noninvasive test. 1, 2

Gold Standard: Invasive HVPG Measurement

HVPG measurement remains the reference standard for diagnosing and quantifying portal hypertension severity 3, 1:

• Portal hypertension is present when HVPG >5 mm Hg 1, 4
• Clinically significant portal hypertension (CSPH) is defined as HVPG ≥10 mm Hg 3, 1, 4
• Severe portal hypertension with high mortality risk is HVPG ≥16 mm Hg 3, 4

However, HVPG is limited by its invasiveness and availability, making it impractical for routine screening 3, 1. This necessitates noninvasive approaches for most clinical scenarios 3.

First-Line Noninvasive Approach: Ultrasound with Doppler

Begin with ultrasound and Doppler examination looking for direct signs of portal hypertension 1, 2:

Direct Signs (100% Specific for CSPH)

• Portosystemic collaterals: recanalized umbilical vein, splenorenal shunts, gastric varices 1, 2
• Portal vein flow reversal (hepatofugal flow) 1, 2
• If either finding is present, CSPH is confirmed with 100% specificity 1, 2

Supportive Findings

• Splenomegaly: sensitive but nonspecific when used alone; valuable when combined with other parameters 1, 2
• Portal vein diameter and velocity: reduced portal vein velocity and increased congestion index can support the diagnosis 2, 5

Second-Line: Transient Elastography (Liver Stiffness Measurement)

When direct ultrasound signs are absent, transient elastography with liver stiffness measurement (LSM) is the best available noninvasive test for detecting CSPH 1:

LSM Interpretation Algorithm

• LSM ≤15 kPa: CSPH is highly unlikely (sensitivity 90-96%) 3, 1, 4
• LSM 15-25 kPa: intermediate zone requiring additional assessment 1
• LSM ≥25 kPa: CSPH is likely present (specificity 82-93%) 3, 1, 4

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, 2.

Blood-Based Tests: Limited Role

Blood-based tests have poor accuracy and should not be used alone to diagnose portal hypertension 1:

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

These tests are substantially less accurate than imaging-based methods 3.

Combined Scoring Systems for Enhanced Accuracy

The Liver stiffness-spleen diameter to platelet ratio score (LSPS) can improve diagnostic accuracy 1, 2:

• LSPS >2.06: 90% specificity for CSPH 1, 2
• LSPS cutoff 0.927 kPa: 99% sensitivity, 54% specificity 1
• LSPS cutoff 3.75 kPa: 52% sensitivity, 97% specificity 1

Clinical Correlation

Interpret all findings alongside clinical signs of portal hypertension 2:

• Spider nevi and visible abdominal collaterals 2
• Laboratory parameters including platelet count and Child-Pugh score 2
• Presence of ascites, varices, or hepatic encephalopathy 3, 4

Common Pitfalls

Important limitations to recognize 3:

• Substantial heterogeneity exists in LSM cutoff values across studies, limiting the ability to establish definitive thresholds 3
• LSM accuracy varies by liver disease etiology, so interpret results in clinical context 3
• Blood-based tests alone are insufficient and should never replace imaging-based assessment 1
• The intermediate LSM zone (15-25 kPa) requires additional evaluation and cannot definitively rule in or rule out CSPH 1