A new diagnostic approach to biliary atresia with emphasis on the ultrasonographic triangular cord sign: comparison of ultrasonography, hepatobiliary scintigraphy, and liver needle biopsy in the evaluation of infantile cholestasis.

BACKGROUND/
PURPOSE: The authors evaluated prospectively the utility of ultrasonography, Tc-99m-DISIDA hepatobiliary scintigraphy, and liver needle biopsy in differentiating biliary atresia (BA) from intrahepatic cholestasis in 73 consecutive infants who had cholestasis.
METHODS: Sixty three ultrasonographic examinations of 61 infants with 7.0-MHz transducer were carried out, focusing on the fibrous tissue at the porta hepatis. The authors defined the triangular cord (TC) as visualization of a triangular or tubular shaped echogenic density just cranial to the portal vein bifurcation on a transverse or longitudinal scan.
RESULTS: Although 17 of 20 ultrasonographic examinations from infants who had BA denoted TC, 43 ultrasonographic examinations from infants with either neonatal hepatitis (NH) or other causes of cholestasis denoted no TC, showing a diagnostic accuracy of 95% with 85% sensitivity and 100% specificity. Investigation with Tc-99m-DISIDA hepatobiliary scintigraphy showed that 24 of 25 infants who had BA had no gut excretion, and 16 of 46 infants who had either NH or other causes of cholestasis had gut excretion, showing a diagnostic accuracy of 56% with 96% sensitivity and 35% specificity. Therefore, gut excretion of tracer excluded BA, but no gut excretion of tracer needed further investigations as liver needle biopsy. Forty-four liver needle biopsies were carried out in 19 infants who had BA and 24 infants who had either NH or other causes of cholestasis. Although 18 of 20 biopsy findings in infants who had BA were correctly interpreted as having BA, 23 of 24 biopsy results in infants who had either NH or other causes of cholestasis were correctly diagnosed, showing a diagnostic accuracy of 93% with 90% sensitivity and 96% specificity.
CONCLUSIONS: Since the introduction of ultrasonographic TC sign in the diagnosis of BA by our institution, we have found that it seemed to be a simple, time-saving, highly reliable, and non-invasive tool in the diagnosis of BA from other causes of cholestasis. The authors propose a new diagnostic strategy in the evaluation of infantile cholestasis with emphasis on ultrasonographic TC sign as first priority of investigations. When the TC is visualized, prompt exploratory laparotomy is mandatory without further investigations. When the TC is not visualized, hepatobiliary scintigraphy is the next step. Excretion of tracer into the small bowel actually rules out BA. Liver needle biopsy is reserved only for the infants with no excretion of tracer. The authors believe that a correct decision regarding the need for surgery can be made in almost all cases with infantile cholestasis by this multidisciplinary approach.