Case discussion
01Clinical context
A neonate with conjugated hyperbilirubinemia underwent abdominal ultrasound to evaluate for biliary atresia, a critical cause of neonatal cholestasis.
02Key imaging findings
Ultrasound shows a contracted, hypoplastic gallbladder measuring about 1.87 cm, with subtle mural irregularity. A hyperechoic triangular cord sign measuring 4.4 mm is seen anterior to the right portal vein. The liver is slightly enlarged (7.0 cm) with normal echotexture and no biliary duct dilatation. Doppler demonstrates patent portal vein (4.3 mm) and hepatic artery (1.5 mm) with subcapsular hepatic arterial flow and an elevated hepatic artery to portal vein diameter ratio (~0.35), all supporting biliary atresia diagnosis.
03Diagnostic reasoning
The diagnosis was established using grayscale ultrasound to assess gallbladder morphology and liver size, identifying a contracted, hypoplastic gallbladder and the triangular cord sign anterior to the right portal vein. Color Doppler imaging evaluated hepatic arterial and portal venous flow, revealing subcapsular hepatic arterial flow and an elevated hepatic artery to portal vein diameter ratio, both supportive of biliary atresia. Absence of intrahepatic biliary dilatation and patent portal vein were also noted, helping exclude other causes.
04Questions for clinical practice
What is the significance of the triangular cord sign?
It is a hyperechoic fibrotic band anterior to the right portal vein, considered a reliable ultrasound marker for biliary atresia.
How does the hepatic artery to portal vein diameter ratio aid diagnosis?
A ratio above 0.34 suggests compensatory hepatic arterial enlargement seen in biliary atresia.
What are the next steps after ultrasound diagnosis?
Urgent referral to pediatric hepatobiliary surgery for clinical correlation, possible hepatobiliary scintigraphy, and consideration of early liver biopsy and surgical intervention.
Can a patent portal vein exclude biliary atresia?
No, the portal vein is usually patent; its presence helps exclude portal vein thrombosis but does not rule out biliary atresia.
05Teaching point
Recognizing the contracted gallbladder, triangular cord sign, subcapsular hepatic arterial flow, and elevated hepatic artery to portal vein ratio on ultrasound and Doppler is crucial for early diagnosis of biliary atresia. Prompt referral for surgical evaluation is essential to improve outcomes.
Shown for education. De-identified — no identifiable patient data. A radiology report is a specialist opinion and must be read with the full clinical context by the treating physician.
