Fasting Before FibroScan
Yes, fasting for at least 3-4 hours before FibroScan is necessary to ensure accurate liver stiffness measurements, as food intake increases hepatic blood flow and can falsely elevate results.
Why Fasting Matters
- Food intake increases hepatic blood flow, which artificially elevates liver stiffness measurements independent of actual fibrosis 1
- The American Association for the Study of Liver Diseases recommends that patients fast for at least 4 hours before the examination to avoid falsely elevated readings 1
- Recent expert panel recommendations from 2024 specify that patients should fast for at least 3 hours before the measurement as part of recommended best practices for vibration controlled transient elastography (VCTE) 2
Technical Best Practices
Beyond fasting, several other factors ensure reliable FibroScan results:
- Obtain ≥10 measurements to ensure statistical validity 2
- Achieve an interquartile range <30% of the median value to confirm measurement consistency 2
- Ensure success rate ≥60% for the examination 2
- Check images to ensure the absence of rib echo, which can interfere with measurements 2
Important Timing Considerations
- Avoid FibroScan during active inflammation or recent alcohol use, as recent alcohol consumption can falsely elevate liver stiffness measurements 1
- For patients with alcohol-related liver disease, ideally perform the test after 2 weeks of abstinence to improve concordance between FibroScan and histology 1, 3
- Elevated AST levels may falsely increase liver stiffness measurements due to superimposed alcoholic steatohepatitis, requiring cautious interpretation 3
Exception for Light Meals
- One research study in lean, healthy volunteers found that intake of a light meal (300 kcal) had no relevant influence on liver stiffness or CAP measurements 4
- However, this finding was in healthy volunteers without liver disease, and guideline recommendations still prioritize fasting for patients undergoing clinical assessment 2, 1
Clinical Pitfall to Avoid
The most common error is performing FibroScan without adequate fasting, which can lead to overestimation of fibrosis stage and inappropriate escalation of care. This is particularly problematic when measurements fall near clinical decision thresholds (e.g., 8 kPa for significant fibrosis, 10-15 kPa for advanced fibrosis) 2.