USG Whole Abdomen Findings in Acute Hepatitis
Abdominal ultrasound is the first-line imaging modality for acute hepatitis and will typically show diffuse hepatic hypoechogenicity, increased portal vein wall thickness, and the characteristic "starry sky" appearance where portal triads appear conspicuous against dark edematous liver parenchyma. 1
Primary Sonographic Features
Hepatic Parenchymal Changes
- Diffuse hepatic hypoechogenicity is the hallmark finding, reflecting acute parenchymal inflammation and edema 1
- Increased thickness of portal vein walls appears as prominent echogenic structures throughout the liver 1
- "Starry sky" appearance manifests as conspicuous portal triads standing out against the background of dark, edematous liver parenchyma 1
- This starry sky pattern can also occur in other conditions such as volume overload, so clinical correlation is essential 1
Hepatic Size and Contour
- Hepatomegaly is present in 52.9% of patients during various phases of acute hepatitis 1, 2
- The liver edge is typically palpable, enlarged, smooth, and tender with firm consistency 2
- Bulging contours may be visible on ultrasound examination 2
Gallbladder Abnormalities
- Contracted gallbladder with wall thickening and edema is a marker of hepatic dysfunction 1
- Gallbladder wall thickening occurs in 75.3% of patients with acute hepatitis 1
- The gallbladder may show contraction or an undulating inner margin 1
Additional Findings
- Perihepatic fluid may be present 1
- Splenomegaly occurs in 56.5% of cases 1
- Periportal edema can be visualized, though this is better appreciated on cross-sectional imaging 1
Important Clinical Caveats
When to Add Duplex Doppler
- Add Duplex Doppler to routine grayscale ultrasound when ischemic hepatitis is suspected to assess vascular patency 1
- This is critical because ischemic liver injury can progress to liver failure with high mortality 1, 2
- Look for hepatic arterial or portal venous occlusion in patients with shock liver or hypotensive episodes 1
Limitations of Ultrasound
- Ultrasound is of limited usefulness in acute hepatitis for establishing specific etiology 3
- The findings are not specific for diagnosis and must be correlated with clinical presentation and laboratory values 3
- Sonography has good but imperfect sensitivity and specificity for parenchymal liver disease 3
When to Escalate to Advanced Imaging
- If ultrasound is equivocal or shows concerning findings, obtain MRI with IV contrast to assess parenchymal inflammation, perfusion abnormalities, and vascular patency 1, 2
- MRI is particularly useful when fulminant hepatitis is suspected, showing hepatic capsular edema and heterogeneous enhancement 1
- CT with IV contrast can identify complications, showing arterial heterogeneity, periportal hypoattenuation, and perihepatic lymphadenopathy (>7 mm) 1
Associated Findings to Document
Lymphadenopathy and Fat Stranding
- Small hepatoduodenal lymphadenopathy is present in 98.8% of cases 1
- Perihepatic fat infiltration occurs in 76.5% of patients 1
Ascites
- Pelvic fluid collection is found in 56.5% of cases 1
- Ascites indicates more severe hepatic dysfunction 1
Severity Indicators
- Gallbladder wall thickness >5.2 mm is an independent predictor of severe hepatitis and prolonged cholestasis 1
- Tender hepatomegaly and gallbladder thickening are important predictors of significant liver involvement 4
Practical Algorithm
- Perform grayscale ultrasound first to evaluate hepatic echogenicity, portal vein walls, liver size/contour, and gallbladder 1
- Add Duplex Doppler immediately if clinical context suggests ischemic injury (shock, hypotension, cardiac disease) 1
- Measure gallbladder wall thickness as values >5.2 mm predict severe disease 1
- Document all associated findings including splenomegaly, ascites, and lymphadenopathy 1
- Escalate to MRI with contrast if findings are equivocal, fulminant hepatitis is suspected, or vascular pathology needs better characterization 1, 2