In a neonate with conjugated hyperbilirubinemia, which imaging study is used to evaluate biliary atresia?

• A. Abdominal ultrasound
• B. MRI
• C. CT scan
• D. Endoscopy

Answer: (A)

When a newborn has conjugated hyperbilirubinemia, biliary atresia is a critical diagnosis to consider because it requires timely surgical management. Abdominal ultrasound is the imaging study used to evaluate for biliary atresia. It’s noninvasive, safe for neonates, and quickly available, making it the best initial test. On ultrasound, clinicians look for signs such as a nonvisualized or abnormally small gallbladder and the triangular cord sign at the porta hepatis, which reflects fibrous tissue encasing the biliary remnant. These findings help distinguish biliary atresia from other causes of neonatal cholestasis, like neonatal hepatitis, where the gallbladder may be present and the triangular cord sign is absent.

If ultrasound doesn’t provide a definitive answer, further testing like hepatobiliary scintigraphy or MRCP can be used, and surgical exploration with intraoperative cholangiography ultimately confirms the diagnosis. Other imaging modalities, such as CT, are less favored in this setting due to radiation and limited added value, and endoscopic procedures are not first-line for initial evaluation in neonates.