Gallbladder contraction in biliary atresia: a pitfall of ultrasound diagnosis.

In 3 (9 %) of 34 children with biliary atresia, US revealed gallbladder contraction following an oral feed, given on admission, but not with subsequent feeds. Surgery revealed a Kasai type IIIa biliary atresia with a patent communication between the gallbladder and duodenum. We propose that the bile ducts may initially have been patent, but then gradually became obliterated secondary to inflammation. These cases may explain the development of one type of biliary atresia.