Diagnostic Significance of Absence of Post-Feeding Contraction of the Gallbladder in Biliary Atresia: Two Case Reports.

Ultrasonography is an essential part of the diagnostic process of biliary atresia (BA). The characteristic findings of BA include a hilar hyperechoic zone, the triangular cord sign (TCS), an absence of gallbladder contraction after feeding, and gallbladder atrophy. However, approximately 10% of patients with BA have a normal gallbladder. We herein present two cases of BA with normal morphology of the gallbladder as shown by ultrasonography. In the first case, the patient was positive for the TCS, negative for gallbladder atrophy, and positive for contraction of the gallbladder after feeding; the final diagnosis was hilar obstructive BA complicated by pancreaticobiliary maljunction. In the second case, the patient was positive for the TCS, negative for gallbladder atrophy, and negative for contraction of the gallbladder after feeding; the patient also had common bile duct obstruction and stenosis of the hepatic duct in the hilar region. Based on these two cases, we conclude that gallbladder findings are not diagnostic for BA because in some types, the gallbladder may be normal in morphology and even have the capacity for contraction after feeding.