Role of abdominal sonography in the preoperative diagnosis of extrahepatic biliary atresia in infants younger than 90 days

The objective of our study was to prospectively assess the role of abdominal sonography in the preoperative diagnosis of extrahepatic biliary atresia (EHBA) in infants younger than 90 days. Sonography was performed in 99 infants younger than 90 days with conjugated hyperbilirubinemia (total bilirubin > 3 mg/dL, conjugated bilirubin > 20% of total) after 4 hours of fasting. They were evaluated for the "triangular cord" sign, the presence and morphology of the gallbladder, gallbladder contraction after oral feeding, the presence and diameter of the common bile duct (CBD), liver size and echotexture, spleen size, caliber of the right branch of the hepatic artery, and caliber of the right branch of the portal vein. The final diagnosis of EHBA was made on basis of surgery. The performance of sonography in the diagnosis of EHBA was evaluated. The study group was composed of 68 boys and 31 girls (age range, 13-89 days); of the 99 infants, 30 had EHBA. The triangular cord sign had a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 23.3%, 97.1%, 77.8%, and 74.4%, respectively. The gallbladder was not visualized in seven infants, all of whom had EHBA. The sensitivity, specificity, PPV, and NPV of an abnormal gallbladder were 83.3%%, 82.6%, 67.6%, and 91.9%, respectively, and for noncontraction of the gallbladder were 87%, 72.5%, 51.3%, and 94.3%, respectively. A nonvisualized CBD had a sensitivity, specificity, PPV, and NPV of 93.3%, 47.8%, 43.8%, and 94.3%, respectively. A negative triangular cord sign with normal gallbladder morphology had an NPV of 91.9% for excluding EHBA. Comprehensive sonographic evaluation can help in segregating infants at high risk of EHBA from those at low risk.