Improving Ultrasound Examination to Identify Biliary Atresia

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A Upton et al. J Pediatr Gastroenterol Nutr. 2025;81:204–211. An ultrasound approach to visualize the “duct at the hilum” in infants undergoing evaluation for biliary atresia

Methods: Ultrasound exams were reviewed from infants undergoing evaluation for biliary atresia at Texas Children’s Hospital during two periods. First, exams performed before 2021 were reviewed to develop a systematic approach to visualize the duct at the hilum (DaH). Second, exams performed during a subsequent 26-month period were reviewed to assess the approach’s diagnostic performance in 64 infants (mean age 25 days).

Key findings:

  • The approach identified all 12 patients with biliary atresia and excluded 49 out of 52 infants without biliary atresia, for a sensitivity of 1.00 and specificity of 0.94.
  • There were three false-positive studies (i.e., the DaH was absent, but diagnosis was not BA) in infants with choledochal cyst, Trisomy 18, and an aberrant main portal vein (which interfered with the US examination),
  • The approach could be performed in feeding infants and often in <5 min.

Discussion:

  • “First, the DaH was easier to identify when infants were allowed to feed. In some cases, a DaH could be seen in fasting images but was longer and more prominent in subsequent non-fasting images”
  • “Tthe approach had high sensitivity and could efficiently rule out infants who did not have biliary atresia”
  • “We have not determined the precise segment of the extrahepatic biliary tree visualized by our approach; however, in contrast to previous reports, we do not think the approach is imaging the “common bile duct.” Rather, the DaH is a segment closer to the liver and could be the common hepatic duct.”
  • “Larger, multisite studies are needed…we may have overestimated sensitivity because the 12 infants with biliary atresia were all categorized as Japanese Biliary Atresia Society classification Type II or III…Similarly, we may have overestimated specificity because all ultrasound exams were performed by 1 sonographer with 10+ years of experience.”
  • Link to instructional video on this technique: jpn370081-sup-0001-Duct_at_the_Hilum_v_001_241127.mp4 985.2 MB

My take: It does seem that the presence of biliary atresia should be identifiable with ultrasound. However, this likely relies on the skills of the ultrasonographer, especially given the small size of these patients. Thus far, in clinical practice, an ultrasound has been mainly helpful at excluding choledochal cysts/anatomic malformations. A tiny or contracted gallbladder (with fasting) does increase the likelihood of biliary atresia. In my experience, other ultrasound findings like the ‘triangular cord’ sign are less helpful than serum matrix metalloproteinase 7 (MMP-7) tests.

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