What is Fibroscan (Fibrosis Scan)?

What is FibroScan?

FibroScan is a non-invasive ultrasound-based device that measures liver stiffness using vibration controlled transient elastography (VCTE) to assess the degree of liver fibrosis without requiring a liver biopsy. 1

Technical Mechanism

FibroScan works by transmitting low-frequency elastic waves (50 Hz) combined with ultrasound (5 MHz) through the liver tissue. 2 The device measures how quickly these shear waves propagate through the liver—stiffer (more fibrotic) liver tissue transmits waves faster than healthy tissue. 2 The result is expressed in kilopascals (kPa), with higher values indicating greater liver stiffness and more advanced fibrosis. 1

The procedure is:

• Rapid: Takes approximately 5 minutes to complete 3
• Painless and non-invasive: No needles or tissue sampling required 2
• Immediate results: Provides real-time measurements during the patient visit 1

Clinical Applications

FibroScan is FDA-approved for use in both adults and children with liver disease. 1 The primary applications include:

• Non-alcoholic fatty liver disease (NAFLD): Used as second-tier testing after FIB-4 score to identify clinically significant fibrosis 1
• Chronic viral hepatitis (B and C): Staging fibrosis to guide treatment decisions 4
• Alcohol-related liver disease: Early assessment in patients with harmful alcohol use 4
• Cirrhosis detection: Regardless of underlying etiology 5
• Monitoring disease progression: Serial measurements over time to track fibrosis changes 3

Interpretation of Results

The key cutoff values for clinical decision-making are:

• **<8.0 kPa**: Rules out clinically significant fibrosis (F2-F4) with >90% negative predictive value; patients can be monitored with repeat testing in 2-3 years 1, 3
• 8.0-12.0 kPa: Indeterminate zone suggesting possible significant fibrosis; requires clinical correlation and potentially additional testing 1
• >12.0 kPa: Indicates likely advanced fibrosis or cirrhosis; warrants hepatology referral for consideration of liver biopsy 1, 4
• >17.6 kPa: Detects cirrhosis with 90% positive and negative predictive value 6

For specific fibrosis stages, FibroScan demonstrates excellent diagnostic accuracy:

• Significant fibrosis (≥F2): Area under ROC curve 0.79-0.88 5, 2
• Severe fibrosis (F3): Area under ROC curve 0.90-0.91 5, 6
• Cirrhosis (F4): Area under ROC curve 0.91-0.99 5, 2, 6

Technical Requirements for Reliability

A FibroScan measurement is only considered valid when ALL three criteria are met: 3, 4

• ≥10 successful measurements obtained during the examination
• Success rate ≥60% of attempted measurements
• Interquartile range <30% of the median value (indicating consistency)

Important Limitations

FibroScan has significant technical limitations that can produce unreliable or failed results: 1

• Obesity: Poor ultrasound beam penetration limits assessment (though XL probes are now available for obese patients) 1
• Ascites: Fluid interferes with wave transmission 1
• Narrow intercostal spaces: Limits probe placement 1, 7
• Acute hepatitis or active inflammation: Falsely elevates stiffness measurements 1, 4
• Extrahepatic cholestasis: Can increase stiffness independent of fibrosis 1
• Recent alcohol consumption: Transiently increases liver stiffness; ideally perform after 2 weeks of abstinence 4
• Passive hepatic congestion: From heart failure can elevate readings 1

Failure rates range from 2-10% depending on patient characteristics, with unreliable results occurring in up to 27% of patients in some studies. 1, 4

Clinical Integration Strategy

FibroScan should NOT be used as a first-line screening tool in unselected populations. 1 The recommended approach is sequential testing:

1. First tier: Calculate simple fibrosis scores (FIB-4 or NAFLD Fibrosis Score) using routine labs (age, AST, ALT, platelet count) 1, 4
2. Second tier: Perform FibroScan for patients with indeterminate scores (FIB-4 1.3-2.67) 1, 3
3. Exception: In alcohol-related liver disease, FibroScan can be used earlier as first-line assessment in patients drinking at harmful levels 4

This sequential approach is more accurate than using either test alone, with studies showing improved diagnostic performance when combining FIB-4 followed by FibroScan for indeterminate cases. 1, 7

Critical Pitfalls to Avoid

• Do not rely on FibroScan alone to exclude other causes of liver disease—it only measures stiffness, not inflammation or alternative diagnoses 4
• Ensure fasting status: Patients should be fasting before the examination to optimize accuracy 1
• Verify technical validity: Always check that the three reliability criteria are met before accepting results 3, 4
• Consider spectrum effect: FibroScan performs differently in low-prevalence (primary care) versus high-prevalence (hepatology clinic) populations, affecting positive and negative predictive values 1
• Avoid during active disease: Do not perform during acute hepatitis flares or within 2 weeks of alcohol consumption 4

Advantages Over Liver Biopsy

FibroScan offers several advantages compared to the traditional gold standard of liver biopsy: 1, 3

• No sampling error: Liver biopsy has 25-60% discordance between samples from the same patient 3
• No procedural risks: Eliminates rare but serious complications including mortality risk from biopsy 1
• Reproducible: Standardized coefficient of variation of only 3% 2
• Operator-independent: When performed correctly, shows minimal inter-operator variability 2
• Cost-effective: Can be performed at point-of-care during clinic visits without additional equipment 1