How do you interpret a FibroScan (Fibrosis Scan) result?

How to Interpret FibroScan Results

FibroScan values should be interpreted using the 2024 WHO-recommended thresholds: >7.0 kPa indicates significant fibrosis (≥F2) and >12.5 kPa indicates cirrhosis (F4) in chronic hepatitis B patients, with these cutoffs prioritizing early detection to prevent progression to cirrhosis and hepatocellular carcinoma. 1

Understanding FibroScan Measurement

FibroScan measures liver stiffness in kilopascals (kPa) using transient elastography, a non-invasive ultrasound-based technique that takes less than 10 minutes to perform and provides immediate results. 1 The measurement correlates with the degree of liver fibrosis based on the METAVIR staging system (F0-F4). 1

Key Diagnostic Thresholds

For Significant Fibrosis (≥F2)

• >6.0 to 8.0 kPa range: Sensitivity 75.1% and specificity 79.3% 1
• WHO 2024 recommended cutoff: >7.0 kPa for identifying most adults with significant fibrosis who are priority candidates for antiviral treatment 1
• In a population with 25% prevalence of significant fibrosis, this cutoff results in 15.8% false positives but only 6.3% false negatives 1

For Advanced Fibrosis (≥F3)

• >8.0 to 11.0 kPa: Sensitivity 80.4% and specificity 85.2% 1
• This range indicates severe fibrosis requiring close monitoring and treatment consideration 1

For Cirrhosis (F4)

• >11.0 to 14.0 kPa range: Sensitivity 82.6% and specificity 89.0% 1
• WHO 2024 recommended cutoff: >12.5 kPa for identifying most adults with cirrhosis 1
• In a population with 5% cirrhosis prevalence, this cutoff results in 10.5% false positives but only 0.9% false negatives 1

For Complications of Cirrhosis

• >17.6 kPa: 90% positive and negative predictive value for cirrhosis diagnosis 2
• >27.5 kPa: Presence of esophageal varices grade 2/3 2
• >37.5 kPa: Child-Pugh B or C cirrhosis 2
• >49.1 kPa: History of ascites 2
• >53.7 kPa: Hepatocellular carcinoma risk 2
• >62.7 kPa: Esophageal bleeding risk 2

Clinical Interpretation Algorithm

Step 1: Assess Result Quality

• Valid measurements require at least 10 successful readings with an interquartile range/median ratio <30% 3
• Failed acquisition occurs in approximately 5% of cases, mainly in patients with substantial thoracic fat 3

Step 2: Apply Disease-Specific Context

• Pre-test probability matters: The diagnostic accuracy depends heavily on baseline prevalence of fibrosis in your patient population 1
• ALT levels significantly affect readings in hepatitis B: Elevated ALT up to 5× upper limit of normal requires higher cutoff values; ALT flares can produce falsely elevated readings in the cirrhotic range 4
• Obesity requires XL probe: Standard M probe has high failure rates in obese patients; XL probe cutoffs are approximately 1.2-1.3 kPa lower than M probe values 4

Step 3: Make Treatment Decisions

• <7.0 kPa: Low probability of significant fibrosis; repeat testing every 1-3 years in at-risk populations 1
• 7.0-12.5 kPa: Significant fibrosis present; prioritize for antiviral treatment to prevent progression 1
• >12.5 kPa: Cirrhosis likely; immediate antiviral treatment indicated and screen for complications (varices, hepatocellular carcinoma) 1
• >17.6 kPa: Definite cirrhosis; comprehensive hepatology evaluation for portal hypertension and cancer surveillance 2

Important Clinical Caveats

False Positives (Overestimation of Fibrosis)

• The WHO 2024 strategy accepts higher false-positive rates (26.2% for significant fibrosis, 10.5% for cirrhosis) to minimize missing patients who need treatment 1
• Acute hepatitis or ALT flares can temporarily elevate readings 4
• Obesity increases stiffness measurements even at the same fibrosis stage 4
• Cholestatic diseases may show elevated readings 3

False Negatives (Underestimation of Fibrosis)

• The current thresholds minimize false negatives (6.8% for significant fibrosis, 0.9% for cirrhosis) because missing patients with fibrosis delays treatment that could prevent progression to cirrhosis or hepatocellular carcinoma 1
• Very early cirrhosis may occasionally fall below diagnostic thresholds 2

When to Use Dual Cutoffs or Additional Testing

• Using both low cutoffs (to rule out) and high cutoffs (to rule in) improves diagnostic accuracy but creates an indeterminate zone requiring retesting, second non-invasive test, or liver biopsy 1
• Consider combining FibroScan with APRI or FIB-4 scores to improve accuracy in the intermediate range 5
• Age, comorbidities (diabetes, metabolic syndrome), and other risk factors (excessive alcohol) affect pre-test probability and should guide interpretation 1, 6

Comparison with Other Non-Invasive Tests

FibroScan outperforms APRI for both significant fibrosis and cirrhosis detection, with higher sensitivity and specificity at comparable cutoffs. 1 However, APRI remains valuable in resource-limited settings due to its low cost (less than a few US dollars per test) versus the equipment investment required for FibroScan. 1