The ultrasonographic 'triangular cord' coupled with gallbladder images in the diagnostic prediction of biliary atresia from infantile intrahepatic cholestasis.

PURPOSE: The aim of this study was to evaluate the importance of the ultrasonographic "triangular cord" (TC) coupled with gallbladder images in the diagnostic prediction of biliary atresia (BA) from infantile intrahepatic cholestasis.
METHODS: Seventy-nine infants with cholestatic jaundice underwent ultrasound examinations, focusing on the TC and gallbladder images. The TC was defined as visualization of a triangular or bandlike periportal echogenicity (3 mm or greater in thickness), which represents a cone-shaped fibrotic mass cranial to the portal vein in infants with BA. An abnormal gallbladder (nonvisualized or small) was thought to be more suggestive of BA than infantile intrahepatic cholestasis.
RESULTS: Among 25 infants with BA, 21 showed TC, whereas 4 had no TC. Fifty-three of 54 infants with infantile intrahepatic cholestasis had no TC, showing a diagnostic accuracy of 94% with 84% sensitivity and 98% specificity. As for positive predictive value in the diagnosis of BA by the TC coupled with gallbladder images, it was 100% when a positive TC was coupled with an abnormal gallbladder and 88% when a positive TC was coupled with a normal gallbladder. It decreased to 25% when a negative TC was coupled with an abnormal gallbladder.
CONCLUSIONS: The TC appears to be a very specific and definite ultrasonographic finding in the early diagnosis of BA. Positive TC regardless of gallbladder images is highly suggestive of BA, showing a 95% positive predictive value, but BA cannot be ruled out when negative TC is coupled with an abnormal gallbladder, requiring further diagnostic modalities such as liver needle biopsy or hepatobiliary scintigraphy.