What is a FibroScan?
FibroScan is a non-invasive ultrasound-based device that measures liver stiffness using transient elastography to assess the degree of liver fibrosis and cirrhosis, providing immediate results in approximately 5 minutes without requiring a blood sample or liver biopsy. 1
How FibroScan Works
Technical Mechanism:
- The device generates a mechanical vibration that creates shear waves through liver tissue, measuring liver stiffness by calculating the velocity of these waves 2
- Results are expressed in kilopascals (kPa), with higher values indicating greater liver stiffness and more advanced fibrosis 2, 3
- The patient lies supine with the right arm raised to widen intercostal spaces, and measurements are taken at 1.5-2 cm depth below the liver capsule through the right upper abdomen 2
- The entire procedure takes approximately 5 minutes and provides immediate results 1, 4
Clinical Applications
Primary Uses:
- Chronic Hepatitis B and C: Staging fibrosis to guide antiviral treatment decisions, with FibroScan >7.0 kPa identifying significant fibrosis (≥F2) and >12.5 kPa identifying cirrhosis 1, 3
- Non-Alcoholic Fatty Liver Disease (NAFLD): Used as a second-line test after FIB-4 score shows indeterminate results (≥1.3) 2
- Alcohol-Related Liver Disease: Immediate assessment recommended for harmful alcohol use, with <8.0 kPa reliably ruling out advanced fibrosis 2
- Cirrhosis Detection: Regardless of etiology, with positive and negative predictive values of 70-95% and 77-95% respectively 5
Interpretation Thresholds
Key Cutoff Values:
- <7.0 kPa: Low probability of significant fibrosis; repeat testing every 1-3 years in at-risk populations 3
- 7.0-8.0 kPa: Significant fibrosis threshold (≥F2); sensitivity 75.1%, specificity 79.3% 3
- 8.0-12.5 kPa: Advanced fibrosis range (F3) 4
- >12.5 kPa: Cirrhosis (F4); sensitivity 82.6%, specificity 89.0%; requires immediate treatment and screening for complications 1, 3
- >17.6 kPa: Cirrhosis detection with 90% positive and negative predictive value 6
Technical Requirements for Reliable Results
A FibroScan result is only considered valid when ALL three criteria are met: 1, 4
- ≥10 successful measurements obtained
- Success rate ≥60%
- Interquartile range <30% of the median value
Advantages Over Liver Biopsy
Key Benefits:
- Completely non-invasive with no risk of bleeding or complications 1
- High reproducibility and accuracy for advanced fibrosis detection 1
- Can be performed repeatedly for monitoring disease progression over time 7
- Painless procedure with excellent patient acceptability 7
- Can be performed in outpatient or community settings by trained non-physician personnel 1
Important Limitations and Pitfalls
Technical Limitations: 1, 4, 2
- Obesity: Failed acquisition common in patients with BMI >28 kg/m² (though XL probe now available for obese patients)
- Ascites: Cannot be performed reliably
- Narrow intercostal spaces: May prevent adequate measurements
- Acute hepatitis: Can falsely elevate liver stiffness measurements
- Extrahepatic biliary tract obstruction: Produces false-positive results
Clinical Considerations:
- Recent alcohol consumption can falsely elevate measurements; ideally perform after 2 weeks of abstinence 2
- Elevated ALT levels (up to 5x upper limit of normal) require higher cutoff values for accurate interpretation in chronic hepatitis B 8
- ALT flare can produce falsely high results in the cirrhotic range 8
- Patients should fast for at least 4 hours before examination, as food intake increases hepatic blood flow and falsely elevates measurements 2
- Failure rates: 1.1-3.5% in Asian populations, 4.3-10.5% in Western populations, primarily due to body habitus differences 2
Comparison to Other Non-Invasive Tests
FibroScan outperforms blood-based tests (APRI, FIB-4) for both significant fibrosis and cirrhosis detection, with higher sensitivity and specificity. 1, 3 However, APRI remains valuable in resource-limited settings due to its extremely low cost (less than a few US$ per test) compared to FibroScan equipment 1