How is a Fibroscan (transient elastography) result interpreted?

Fibroscan (Transient Elastography) Interpretation

Fibroscan results are interpreted using specific kilopascal (kPa) thresholds that vary by disease etiology, with values <7-8 kPa generally excluding significant fibrosis, 8-12.5 kPa indicating progressive fibrosis stages, and >12.5 kPa suggesting cirrhosis. 1

Technical Validity Requirements

Before interpreting any Fibroscan result, ensure the measurement meets quality criteria:

• At least 10 successful measurements must be obtained 1, 2
• Success rate must be ≥60% 1, 2
• Interquartile range (IQR) must be <30% of the median value 1, 2
• Patient should fast for at least 4 hours before examination, as food intake increases hepatic blood flow and falsely elevates readings 1, 2

Results failing these criteria should not be used for clinical decision-making. 2

Disease-Specific Interpretation Thresholds

Chronic Hepatitis C

For significant fibrosis (≥F2):

• Cutoff values range from 7.1 to 8.8 kPa with AUROC 0.79-0.83 1
• Use 7.0 kPa as the practical threshold for identifying significant fibrosis 2

For cirrhosis (F4):

• Cutoff values range from 12.5 to 14.6 kPa with AUROC 0.95-0.97 1
• 12.5 kPa is the recommended threshold for detecting cirrhosis 1, 2
• This threshold has 77-78% positive predictive value and 95-97% negative predictive value 1

Post-SVR patients:

• Use 9.5 kPa cutoff to rule out advanced fibrosis after successful hepatitis C treatment 1
• Values <9.5 kPa suggest patients can be discharged from dedicated liver clinics if they have no other risk factors 1

Chronic Hepatitis B

• APRI score >0.5 or Fibroscan >7.0 kPa identifies significant fibrosis (≥F2) 2
• APRI score >1.0 or Fibroscan >12.5 kPa identifies cirrhosis 2
• Sensitivity/specificity is 70%/84% for significant fibrosis and 87%/91% for cirrhosis 2

Non-Alcoholic Fatty Liver Disease (NAFLD)

Stepwise approach is critical:

• First calculate FIB-4 score using routine labs (AST, ALT, platelet count, age) 2, 3
• FIB-4 <1.3 (<2.0 if age >65 years) reliably excludes advanced fibrosis with ≥90% negative predictive value 2, 3
• FIB-4 >2.67 indicates high risk (60-80% positive predictive value) and warrants hepatology referral regardless of Fibroscan 2

For intermediate FIB-4 scores (1.3-2.67), use Fibroscan:

• <8.0 kPa rules out advanced fibrosis in NAFLD patients 2, 3
• 8.0-12.0 kPa indicates progressive fibrosis requiring closer monitoring 3
• >12.0 kPa suggests cirrhosis and requires hepatology referral 3

Alcohol-Related Liver Disease

• <8.0 kPa reliably rules out advanced fibrosis 2
• Perform Fibroscan immediately in patients with harmful alcohol use (≥35 units/week for women, ≥50 units/week for men) 2
• Avoid testing during active drinking or within 2 weeks of alcohol consumption, as recent alcohol falsely elevates liver stiffness 2

Portal Hypertension and Varices Assessment

For detecting high-risk esophageal varices:

• 27.5 kPa cutoff for presence of esophageal varices stage 2/3 4, 5
• 23.3 kPa cutoff predicts at least grade 2 esophageal varices 5
• Values >49.9 kPa for splenic stiffness or >12.0 kPa for liver stiffness warrant endoscopy referral 6

Additional cirrhosis severity markers:

• 37.5 kPa: Child-Pugh B or C cirrhosis 4
• 49.1 kPa: Past history of ascites 4
• 53.7 kPa: Hepatocellular carcinoma risk 4
• 62.7 kPa: Esophageal bleeding risk 4

Critical Interpretation Pitfalls

Factors That Falsely Elevate Readings

Acute hepatitis with severe inflammation and necrosis causes falsely high results despite mild fibrosis 1, 7

Elevated ALT levels significantly affect interpretation:

• Patients with the same fibrosis stage but higher ALT have higher liver stiffness measurements 8
• The diagnostic accuracy for cirrhosis is lower (AUROC 0.86) when ALT is above upper limit of normal compared to normal ALT (AUROC 0.93) 8
• Transient elastography may overestimate fibrosis when ALT is elevated 8

Other confounding factors:

• Extrahepatic cholestasis 1
• Passive hepatic congestion 1
• Hepatic edema 1
• Recent food intake (within 4 hours) 1, 2

Technical Failure Scenarios

Fibroscan cannot be performed or produces unreliable results in:

• Obesity (BMI >28 kg/m²), though XL probe may help 1, 2
• Ascites 1, 7
• Narrow intercostal spaces 1, 3
• Failure rates: 1.1-3.5% in Asian populations, 4.3-10.5% in Western populations (primarily due to body habitus) 1

Integration with Clinical Context

Fibroscan measures liver stiffness, not fibrosis directly 7

Results must be interpreted alongside:

• Clinical presentation and physical examination findings 7
• Laboratory values (AST, ALT, platelet count, bilirubin) 1, 2
• Imaging findings 7
• Disease etiology and activity 7, 8

Do not rely on Fibroscan alone to rule out other causes of liver disease, as it only measures stiffness and cannot diagnose alternative etiologies 2

Follow-Up Testing Intervals

• Low-risk patients (FIB-4 <1.3 and Fibroscan <7.8 kPa): Repeat in 3-5 years if risk factors persist 2
• NAFLD patients with FIB-4 <1.3: Re-evaluate after 1-2 years if prediabetes, type 2 diabetes, or ≥2 metabolic risk factors present; after 2-3 years if NAFLD without diabetes 2
• Intermediate risk patients: Repeat Fibroscan in 2-3 years 3

When to Refer to Hepatology

Urgent referral indicated when:

• Fibroscan >12.5 kPa (suggests cirrhosis and requires HCC screening) 2
• FIB-4 >3.25 or NFS >0.675 regardless of Fibroscan result 2
• Fibroscan >12.0 kPa with consideration for liver biopsy 3