‘Triangular Cord’: A Sonographic Finding Applicable in the Diagnosis of Biliary Atresia

Abstract

Biliary atresia (BA) is characterized by luminal obstruction of the extrahepatic bile duct with fibrous remnants. The authors reviewed ultrasonographic examinations of the fibrous tissue in the bifurcation of the portal vein at the porta hepatis and identified the triangular- or tubular-shaped echogenic density, the so-called “triangular cord” (TC), in the vicinity of the portal vein on a transverse or longitudinal scan. In this prospective study, the authors investigated whether TC was useful in the noninvasive diagnosis of biliary atresia in 18 infants who had persistent neonatal jaundice. This was done by comparing the ultrasonographic examination with the histopathologic examination (HPE) of liver specimens obtained from a needle biopsy. The TC was identified in nine patients, all of whom were confirmed to have BA by HPE. The TC was not observed in the other nine patients, who had neonatal hepatitis (NH). The mean size of the TC was 13 mm (wide) × 6 mm (thick) (width range, 5 to 21 mm; thickness range, 4 to 12 mm). The diagnosis of BA was confirmed at the time of Kasai hepatoportojejunostomy in eight of the nine patients whose TC was noted by ultrasonography (US). The other patient was discharged because his parents refused the operation; he died of liver failure at 15 months of age. The nine patients with absent TC were treated medically for NH. Eight of them improved clinically. The other, diagnosed to have NH by needle and wedge liver biopsies, was reexamined 40 days after the initial examination because of worsening jaundice. A 18 × 12-mm TC was visualized ultrasonographically. Additionally, a percutaneous liver biopsy specimen showed BA with severe portal fibrosis and ductal proliferation. The patient underwent a Kasai hepatoportoenterostomy. On the basis of these results, the authors conclude that TC is a very specific ultrasonographic finding, representing the fibrous cone at the porta hepatis, and is a useful tool in the noninvasive diagnosis of BA. However, early exploration or close US follow-up is recommended for any patient suspected of having BA clinically, even if a liver biopsy confirms the NH.