Introduction

Differentiating biliary atresia (BA) from Alagille Syndrome (AGS) is critical but challenging. While a positive “triangular cord sign” (echogenicity >4 mm) is a known ultrasound marker for BA, this study investigates whether a thin echogenicity at the anterior aspect of the right portal vein can aid identifying AGS.

Methods

Maximum echogenicity (MxE) measurements were taken from ultrasound images by locating the thickest echogenicity along the right portal vein's anterior wall and measuring its thickness. MxE measurements were retrospectively analyzed in infants with BA (n=12) and AGS (n=30). Ultrasound images were reviewed to measure MxE at the anterior wall of the right portal vein using standardized criteria. Clinical characteristics and diagnostic thresholds were compared across groups.

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Results

Infants with BA had MxE values ranging from 2.5 to 5.0 mm (mean ± SD: 3.9 ± 0.8 mm), with none having MxE <1.0 mm. In contrast, infants with AGS had significantly thinner MxE, ranging from 0.5 to 3.3 mm (mean ± SD: 1.1 ± 0.6 mm). Notably, 16 of 30 AGS infants had MxE <1.0 mm. These findings suggest that a threshold of MxE <1.0 mm may help exclude BA and identify AGS.

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Conclusion

A thin echogenicity (MxE <1.0 mm) at the anterior right portal vein may serve as a useful non-invasive marker for AGS, reducing unnecessary invasive testing and inappropriate treatment in affected infants (Figure B). Larger studies are needed to validate these results and explore the potential for combining MxE with other ultrasound markers to improve diagnostic accuracy.