Accuracy of echogenic periportal enlargement image in ultrasonographic exams and histopathology in differential diagnosis of biliary atresia.

OBJECTIVES To define the sensitivity, specificity and accuracy of the ultrasound triangular cord sign and hepatic histopathology, in isolation or in combination, for diagnostic differentiation between biliary atresia and intrahepatic cholestasis. METHODS This was a retrospective study carried out between January 1990 and December 2004. Fifty-one cases of biliary atresia and 45 of intrahepatic cholestasis were analyzed. Histopathology was performed blind by a pathologist. The triangular cord sign was identified in ultrasound reports as the only diagnostic sign of biliary atresia. Sensitivity, specificity and accuracy were calculated for the triangular cord sign and histology both in isolation and in combination. The gold standard for diagnosis of biliary atresia was the appearance of the extrahepatic biliary tree via laparotomy. RESULTS The triangular cord sign alone had sensitivity of 49%, specificity of 100% and accuracy of 72.5%. Histopathology compatible with extrahepatic biliary obstruction alone had 90.2% sensitivity, 84.6% specificity and 87.8% accuracy. The triangular cord sign and histopathology in isolation or combination resulted in sensitivity of 93.2%, specificity of 85.7% and accuracy of 90.3%. CONCLUSIONS Finding the triangular cord sign on ultrasound is an indication for laparotomy. If the triangular cord sign is negative, liver biopsy is indicated; if histopathology reveals signs of biliary atresia, explorative laparotomy is indicated. In cases where the triangular cord sign is absent and histopathology indicates neonatal hepatitis or other intrahepatic cholestasis, clinical treatment or observation are recommended in accordance with the diagnosis.