Biliary atresia: US diagnosis

Purpose: To evaluate prospectively the sensitivity of ultrasonography (US) in the diagnosis of biliary atresia (BA), with surgery as the reference standard. Materials and Methods: After institutional ethical approval and with informed parental consent, 90 consecutive fasting infants with conjugated hyperbitirubinemia underwent detailed US studies performed by a single operator with a 7.5-MHz curvilinear transducer and a 13.5-MHz linear-array transducer. Tile following features were prospectively recorded: gallbladder morphology, triangular cord sign, presence of a common bile duct, liver size and echotexture, splenic appearance, and vascular anatomy. The operator was blinded to results of other investigations. Sensitivity, specificity, and positive and negative predictive values were calculated for each US variable. BA and non-BA groups were compared by means of the Fisher exact test for categorical variables and an unpaired t test for continuous variables. Results: Thirty infants (13 male, 17 female) had surgically confirmed BA, and 60 (35 male, 25 female) had other documented causes of neonatal jaundice; the mean ages at US assessment were 48.5 and 52.4 days, respectively (P > .5). Eight US features showed a significant difference between BA and non-BA groups (P < .001, Fisher exact test). The features with the greatest individual sensitivity and specificity, respectively, in the diagnosis of BA were triangular cord sign (73% and 100%), abnormal gallbladder wall (91 % and 95%) and shape (70% and 100%), and an absent common bile duct (93% and 92%). The hepatic artery diameter was significantly larger in infants with BA than in those without BA (mean +/- standard deviation, 2.2 mm +/- 0.59 vs 1.6 mm +/- 0.40, P < .001), but portal vein diameters were not significantly different. By means of all these US features, 88 of 90 infants were correctly classified as having or not having BA, for an overall accuracy of 98%. Conclusion: BA can be distinguished with US from other causes of conjugated hyperbiliruhinemia in 98% of infants if multiple US features are carefully evaluated.