Sonographic triangular cord sign and gallbladder abnormalities diagnostic for biliary atresia

1. This meta-analysis found that for newborns presenting with jaundice, the triangular cord sign and abnormal gallbladder characteristics on ultrasound were most useful in the diagnosis or exclusion of biliary atresia.

2. The sensitivity and specificity for the combination of the triangular cord sign and gallbladder abnormalities for biliary atresia was superior to that of either feature alone.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Biliary atresia is a rare but severe disease in which bile excretion is blocked due to a viral or autoimmune-induced obstruction or congenital absence of the ducts causing progressive compromise of digestive function, impaired excretion of hepatic waste. Although newborns with biliary atresia typically appear healthy at birth, jaundice and other hepatic symptoms manifest between the first 2 weeks to 2 months of life. Prompt diagnosis and surgical drainage by Kasai portoenterostomy are required to avoid serious liver damage and mortality, and these patients will typically still go on to require liver transplantation. Biliary atresia is typically diagnosed with a combination of serum bilirubin, liver biopsy and various imaging modalities, including ultrasound. The identification of a triangular cord sign on ultrasound has been suggested as a noninvasive and cost-effective tool in the diagnosis of biliary atresia. The triangular cord sign is defined as a trigular or tubular echogenic density near the portal vein, and is indicative of fibrous ductal remnant at the anterior component of the portal vein at its bifurcation. In order to investigate the diagnostic performance of ultrasound in the evaluation of biliary atresia, the researchers reviewed 23 studies involving jaundiced neonates and infants with suspected biliary atresia who received diagnostic ultrasound and subsequently underwent surgical or pathologic confirmation. Features on sonography such as the triangular cord sign and gallbladder abnormalities were reviewed to determine their sensitivity and specificity, and were found to be the most useful characteristics for either the diagnosis or exclusion of biliary atresia, followed by signs such as hepatic artery enlargement, with the former being the most specific. Gallbladder abnormalities included small size, abnormal wall features, dysmotility or absence. However, these conclusions were limited as the studies selected displayed significant heterogeneity, including a wide reported range of sensitivities and specificities for the sonographic features of interest, variable definitions of the triangular cord sign, and variable exclusion or inclusion criteria, including the exclusion of cystic biliary atresia from some studies.

Click to read the study in the American Journal of Roentgenology

Relevant Reading: Evaluation of the triangular cord sign in the diagnosis of biliary atresia

In-Depth [meta-analysis]: This meta-analysis identified studies based on an indexed term search (“triangular cord OR gall bladder AND biliary atresia”) within MEDLINE and Web of Sciences databases for English-language articles published between January 1990 and May 2015. The 23 selected neonate and infant ultrasound studies each included 2 × 2 contingency data on diagnostic performance of ultrasonography in identifying biliary atresia as well as additional reference standard information based on follow-up surgery, biopsy, clinical follow-up, or a combination of the 3. Other inclusion criteria for this meta-analysis required that each study enrolled at least 10 patients with and 10 patients without the disease. The triangular cord sign was found to have the highest diagnostic accuracy for biliary atresia with an overall sensitivity of 0.74 (CI95%: 0.61–0.84) and specificity of 0.97 (CI95%: 0.95–0.99), calculated from 20 studies. From 19 studies, the summary sensitivity and specificity for gallbladder abnormalities were respectively 0.85 (CI95%: 0.76–0.91) and 0.92 (CI95%: 0.81–0.97). Diagnostic performance when a combination of both triangular cord sign and gallbladder abnormalities on ultrasound was superior to diagnosis based on either characteristic alone, with a sensitivity and specificity of 0.95 (CI95%: 0.70–0.99) and 0.89 (CI95%: 0.79–0.94), respectively.

Image: CC/Wiki/Chardot C. Biliary atresia

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