Ultrasound Findings in PFIC in Children
In children with Progressive Familial Intrahepatic Cholestasis (PFIC), abdominal ultrasound typically shows normal or non-dilated bile ducts, which is the key finding that distinguishes PFIC from extrahepatic biliary obstruction, along with hepatomegaly and coarse/heterogeneous liver parenchymal texture. 1, 2
Primary Ultrasound Characteristics
The hallmark ultrasound finding in PFIC is the absence of biliary ductal dilatation, which helps differentiate this intrahepatic cholestasis from mechanical obstruction such as biliary atresia. 1 This is critical because PFIC represents a disorder of canalicular secretion rather than ductal obstruction. 1
Specific Sonographic Features:
Hepatomegaly is consistently present on ultrasound examination in children with PFIC. 2, 3
Coarse or heterogeneous liver parenchymal texture reflects the underlying hepatocellular injury and progressive fibrosis. 2
Normal-caliber intrahepatic and extrahepatic bile ducts - this is the distinguishing feature that rules out obstructive causes. 1
Splenomegaly may be present as the disease progresses to cirrhosis and portal hypertension. 3
Clinical Context and Diagnostic Approach
The European Association for the Study of the Liver guidelines emphasize that abdominal ultrasonography is the first-line imaging modality to exclude dilated ducts and mass lesions because it is sensitive, specific, non-invasive, portable, and relatively inexpensive. 1 However, ultrasound has important limitations - findings are operator-dependent and bile duct abnormalities may be missed. 1
Key Diagnostic Pitfall:
When ultrasound shows non-dilated ducts in an infant with cholestasis, biliary atresia must still be ruled out urgently (before 60 days of age) using hepatobiliary scintigraphy (HIDA scan) or intraoperative cholangiography, as early biliary atresia may not show ductal dilatation on ultrasound. 4, 2 The American Academy of Pediatrics prioritizes excluding biliary atresia first because it requires urgent Kasai portoenterostomy to prevent irreversible liver damage. 4
Biochemical Correlation
The ultrasound finding of non-dilated ducts combined with low or normal gamma-glutamyl transferase (GGT) levels and conjugated hyperbilirubinemia is the characteristic pattern that strongly suggests PFIC types 1 or 2 rather than biliary atresia or other cholestatic conditions. 4, 5, 3
Advanced Imaging Considerations
If ultrasound findings are equivocal or clinical suspicion for biliary obstruction remains high despite normal ultrasound, magnetic resonance cholangiopancreatography (MRCP) should be performed to definitively visualize the biliary tree, though this is rarely necessary when the clinical and biochemical picture clearly indicates PFIC. 1