How do I interpret a Fibroscan (Fibrosis Scan) report for a patient with potential liver disease, considering their medical history and liver function tests?

Understanding and Interpreting FibroScan Reports

FibroScan provides two key measurements: liver stiffness measurement (LSM) in kilopascals (kPa) to assess fibrosis stage, and controlled attenuation parameter (CAP) in dB/m to quantify hepatic steatosis—both values must be interpreted in the context of the underlying liver disease etiology, technical validity criteria, and the patient's metabolic risk factors. 1

Technical Validity Requirements

Before interpreting any FibroScan result, verify the examination meets all three technical validity criteria 1:

• ≥10 successful measurements obtained 1
• Success rate ≥60% 1
• Interquartile range (IQR) <30% of the median LSM value 1

If these criteria are not met, the result is unreliable and should be documented as "technically inadequate" rather than using the numerical value for clinical decisions. 1 High IQR values (≥30%) indicate measurement inconsistency from patient movement, inadequate fasting, obesity, narrow intercostal spaces, or operator inexperience. 1

Pre-Test Considerations That Affect Results

Several factors can falsely elevate liver stiffness measurements independent of fibrosis 1:

• Recent food intake (patients must fast ≥3-4 hours before examination) 1
• Active hepatic inflammation or acute hepatitis 2, 1
• Recent alcohol consumption (ideally test after 2 weeks of abstinence) 1
• Extrahepatic cholestasis or biliary obstruction 1
• Right heart failure or passive hepatic congestion 1

Liver Stiffness Measurement (LSM) Interpretation by Disease Etiology

For NAFLD/Metabolic-Associated Fatty Liver Disease

The American Gastroenterological Association and European Association for the Study of the Liver provide the following thresholds 1, 3, 4:

• <8.0 kPa: Rules out advanced fibrosis with 93% sensitivity; indicates F0-F1 (no to minimal fibrosis) 1, 3
• 8.0-12.0 kPa: Indeterminate risk zone; may represent F2-F3 (significant to advanced fibrosis) 1, 3
• >12.0-12.5 kPa: High probability of cirrhosis (F4); requires urgent hepatology referral and hepatocellular carcinoma surveillance 1, 3

The optimal Youden cutoff for detecting significant fibrosis (≥F2) in NAFLD is 8.2 kPa (rounded to 8.0 kPa clinically). 4

For Chronic Viral Hepatitis (HBV/HCV)

Use APRI score in conjunction with FibroScan for improved accuracy 2, 1:

• APRI >0.5 OR FibroScan >7.0 kPa: Identifies significant fibrosis (≥F2) 1
• APRI >1.0 OR FibroScan >12.5 kPa: Identifies cirrhosis 1
• FibroScan sensitivity/specificity: 70%/84% for significant fibrosis; 87%/91% for cirrhosis 1

For Alcohol-Related Liver Disease

• <8.0 kPa: Reliably rules out advanced fibrosis 1
• >15 kPa with platelets <150,000: Highly suggestive of compensated advanced chronic liver disease (cACLD) 2

For Assessing Clinically Significant Portal Hypertension

• >20-25 kPa: Diagnoses clinically significant portal hypertension (CSPH) with AUROC 0.93, indicating need for variceal screening 1
• ≥21 kPa: Predicts clinical decompensation events with prognostic value equal to hepatic venous pressure gradient ≥10 mmHg 1

Controlled Attenuation Parameter (CAP) Interpretation

CAP quantifies hepatic steatosis in dB/m 4:

• <248-302 dB/m: Minimal to no steatosis (S0-S1) 1, 4
• ≥302 dB/m: Any steatosis (≥S1) with AUROC 0.87 4
• ≥331 dB/m: Moderate steatosis (≥S2) with AUROC 0.77 4
• ≥337 dB/m: Severe steatosis (S3) with AUROC 0.70 4

Important caveat: CAP accuracy decreases as steatosis severity increases, with the lowest AUROC for severe steatosis. 4

Algorithmic Approach to FibroScan Ordering

The American Association for the Study of Liver Diseases and European Association for the Study of the Liver recommend a stepwise approach 1:

Step 1: Calculate FIB-4 Score First

FIB-4 = (Age × AST) / (Platelet count × √ALT) 1

Step 2: Determine Need for FibroScan Based on FIB-4 and Clinical Context

For NAFLD patients 1:

• FIB-4 <1.3 (<2.0 if age ≥65): Repeat in 2-3 years without FibroScan
• FIB-4 1.3-2.67 (indeterminate zone): Proceed to FibroScan
• FIB-4 >2.67: High risk; refer to hepatology regardless of FibroScan

For patients with harmful alcohol use (≥35 units/week for women, ≥50 units/week for men): Order FibroScan immediately as first-line test 1

For chronic hepatitis B or C: Order FibroScan to guide antiviral therapy decisions 1

Management Based on FibroScan Results

Low-Risk Results (LSM <8.0 kPa)

• Repeat surveillance in 2-3 years if metabolic risk factors persist 1, 3
• Repeat in 3-5 years if risk factors well-controlled 1
• Continue addressing underlying metabolic risk factors (weight loss, diabetes control, lipid management) 3

Indeterminate Results (LSM 8.0-12.0 kPa)

• Refer to hepatology for monitoring 1
• Re-evaluate in 2-3 years 1
• Consider MR elastography or liver biopsy if clinical decision-making requires definitive staging 1

High-Risk Results (LSM >12.0 kPa)

• Urgent hepatology referral 1
• Initiate hepatocellular carcinoma surveillance (ultrasound ± AFP every 6 months) 1
• Screen for esophageal varices with upper endoscopy 1
• Consider liver biopsy or MR elastography for definitive staging 1

Special Populations Requiring Particular Attention

Type 2 Diabetes Patients

69.2% have NASH and 41.0% have advanced fibrosis on biopsy, even with borderline FIB-4 scores. 1 These patients warrant FibroScan even with FIB-4 in the low-intermediate range, particularly if diabetes duration >10 years or age >50 years. 1

Patients with Multiple Metabolic Risk Factors

Presence of obesity (BMI >35), diabetes, dyslipidemia, and hypertension increases fibrosis risk exponentially. 1 These patients require more aggressive surveillance with repeat FibroScan every 6-12 months if LSM is borderline (7-8 kPa). 3

Post-Viral Hepatitis Cure

All patients with previous HCV (now RNA-negative) or resolved HBV should be screened for advanced fibrosis despite successful antiviral therapy, as they remain at risk for hepatocellular carcinoma and portal hypertension complications. 2 Those with previous diagnosis of advanced fibrosis/cirrhosis require continued hepatological follow-up despite LSM improvement. 2

Common Pitfalls and How to Avoid Them

Pitfall #1: Performing FibroScan without adequate fasting leads to overestimation of fibrosis stage, particularly problematic when measurements fall near clinical decision thresholds (8 kPa, 10-15 kPa). 1 Solution: Ensure ≥3-4 hours fasting before examination. 1

Pitfall #2: Using FibroScan alone without calculating FIB-4 first misses the opportunity for cost-effective initial risk stratification. 1 Solution: Always calculate FIB-4 using routine labs (AST, ALT, platelets, age) before ordering FibroScan. 1

Pitfall #3: Relying on normal ALT to exclude significant fibrosis—18-43% of patients with normal ALT have significant fibrosis on biopsy, particularly those >35-40 years. 3 Solution: Use FibroScan in high-risk patients regardless of ALT levels. 3

Pitfall #4: Ignoring technical validity criteria and using unreliable measurements for clinical decisions. 1 Solution: Document IQR, success rate, and number of measurements; reject results not meeting validity criteria. 1

Pitfall #5: Assuming FibroScan rules out other liver diseases—it only measures stiffness, not inflammation or alternative diagnoses. 1 Solution: Complete workup for viral hepatitis, autoimmune liver disease, hemochromatosis, Wilson disease, and alcohol use before attributing findings solely to NAFLD. 2

Pitfall #6: Using NAFLD cutoffs for other etiologies—cutoff values are disease-specific and not transferrable between conditions. 5 Solution: Apply etiology-specific thresholds as outlined above. 1

Technical Limitations Requiring Alternative Testing

FibroScan cannot be performed reliably or may fail in 2, 1:

• Severe obesity (BMI >28-30 kg/m²)—consider XL probe if available 2, 1
• Ascites 2, 1
• Narrow intercostal spaces 2, 1
• Acute hepatitis 1
• Extrahepatic biliary tract obstruction 1

In these situations, consider MR elastography or proceed directly to liver biopsy. 1

Integrating FibroScan with Other Clinical Data

Never interpret FibroScan in isolation. 1 Synthesize results with:

• Imaging findings: Irregular liver surface, caudate lobe hypertrophy, splenomegaly, or portal vein diameter >13 mm suggest advanced disease 2
• Laboratory markers: Thrombocytopenia (<150,000), hypoalbuminemia, elevated INR, or elevated bilirubin indicate synthetic dysfunction 2
• Clinical signs: History of variceal bleeding, ascites, hepatic encephalopathy, or hepatocellular carcinoma definitively establishes cirrhosis regardless of LSM 2

When FibroScan and clinical data are discordant (e.g., ultrasound shows cirrhosis but LSM <10 kPa, or vice versa), calculate APRI score and consider liver biopsy or MR elastography for definitive staging. 1