How is portal hypertension diagnosed and managed?

Diagnosis of Portal Hypertension

Gold Standard Diagnostic Method

Portal hypertension is definitively diagnosed by measuring the hepatic venous pressure gradient (HVPG), which is calculated as the difference between wedged hepatic venous pressure and free hepatic venous pressure. 1, 2

HVPG Thresholds and Clinical Significance

• Normal HVPG: 1-5 mmHg 1, 3
• Portal hypertension present: HVPG ≥6 mmHg 1, 3
• Clinically significant portal hypertension (CSPH): HVPG ≥10 mmHg, at which point complications such as esophageal varices and ascites develop 1, 2, 3
• High-risk threshold: HVPG ≥12 mmHg indicates risk of variceal bleeding 1
• High mortality threshold: HVPG ≥16 mmHg is independently associated with higher mortality in both compensated and decompensated cirrhosis 1, 3
• Acute bleeding predictor: HVPG ≥20 mmHg predicts failure to control bleeding, early rebleeding, and death during acute variceal hemorrhage 1

Limitations of HVPG

Despite being the gold standard, HVPG measurement requires specific expertise, is invasive, relatively expensive, and not available in all centers, making it not standard of care for every patient with cirrhosis. 1

Important caveat: HVPG remains normal in prehepatic (portal vein thrombosis) and presinusoidal causes of portal hypertension because wedged pressure does not reflect portal pressure in these conditions. 1, 4

Non-Invasive Diagnostic Approach

Physical Examination

Look for specific signs of portal hypertension on physical examination, including spider nevi and visible abdominal portosystemic collaterals, though their absence cannot rule out CSPH. 1

Laboratory Testing

• Platelet count: Low platelet count is the most common laboratory sign of portal hypertension and correlates with HVPG and presence of gastroesophageal varices, though taken alone it is not accurate enough to diagnose or exclude CSPH. 1
• Combination approach: Platelet count combined with other noninvasive tests improves diagnostic accuracy for CSPH. 1

Imaging Studies

Abdominal Ultrasound with Doppler

Ultrasound is the primary imaging modality for diagnosing portal hypertension, providing safe and inexpensive evidence of morphological abnormalities. 1

• 100% specific findings for CSPH: Presence of portocollateral circulation (recanalized paraumbilical vein, spontaneous splenorenal circulation, dilated left and short gastric veins) or reversal of flow within the portal system 1
• Color-Doppler examination: Differentiates passive portal hypertension from right heart failure versus portal hypertension from increased trans-hepatic venous gradient with liver cirrhosis 1
• Splenomegaly: Sensitive but nonspecific sign; when combined with platelet count and liver stiffness, provides accurate data on CSPH/varices 1
• Other sonographic signs: Portal vein dilatation, reduced portal vein velocity, and congestion index of portal vein 1

Transient Elastography (FibroScan)

Liver stiffness measurement by transient elastography has proven very accurate for discriminating patients with and without CSPH, with a mean AUROC of 0.93. 1

Advanced Imaging

Computed tomography (CT) and magnetic resonance imaging can detect portosystemic collaterals and provide supportive evidence for portal hypertension. 1, 5

Diagnostic Algorithm

Step 1: Clinical Suspicion

Evaluate patients with known chronic liver disease, cirrhosis, or presenting symptoms (variceal bleeding, ascites, splenomegaly). 2, 6

Step 2: Initial Non-Invasive Assessment

• Perform abdominal ultrasound with Doppler to assess liver morphology, splenomegaly, and portosystemic collaterals 1
• Check platelet count and consider liver stiffness measurement by transient elastography 1
• If portocollateral circulation or flow reversal is present on ultrasound, CSPH is confirmed without need for HVPG 1

Step 3: HVPG Measurement (When Indicated)

Consider invasive HVPG measurement when:

• Non-invasive tests are equivocal 1
• Precise quantification is needed for prognostication 1, 2
• Monitoring therapeutic response is required 3
• Differentiating types of portal hypertension (prehepatic vs. intrahepatic vs. posthepatic) 1

Step 4: Assess for Complications

Once portal hypertension is diagnosed, evaluate for:

• Varices: Upper endoscopy to screen for esophageal and gastric varices 2, 6
• Ascites: Diagnostic paracentesis with measurement of ascitic fluid albumin/protein, neutrophil count, culture, and amylase when present 2
• Other complications: Hepatic encephalopathy, hepatorenal syndrome, hepatic hydrothorax 2, 3

Classification by Anatomical Location

Portal hypertension should be classified by the site of increased resistance to blood flow: 1, 4

• Prehepatic: Portal vein thrombosis, splenic vein thrombosis (HVPG normal) 1, 4
• Intrahepatic: Cirrhosis from any cause (most common in Western countries), including viral hepatitis, alcohol, NASH, autoimmune hepatitis (HVPG elevated) 1, 4
• Posthepatic: Budd-Chiari syndrome, sinusoidal obstruction syndrome, right heart failure (HVPG elevated) 1, 4

Common Pitfalls

• Do not rely on platelet count alone to diagnose or exclude CSPH, as it lacks sufficient accuracy when used in isolation 1
• Remember that HVPG is normal in prehepatic and presinusoidal portal hypertension, so a normal HVPG does not exclude these causes 1, 4
• Splenomegaly alone is nonspecific and must be interpreted in combination with other findings 1
• HVPG measurement is not universally available or necessary for all patients; non-invasive methods are increasingly utilized and acceptable for routine clinical practice 1