Diagnostic Accuracy of Hepatic Subcapsular Flow on Color Doppler Ultrasonography and Preoperative Liver Biopsy for the Diagnosis of Biliary Atresia in Neonatal Cholestasis: A Pilot Diagnostic Accuracy Study.

Background Biliary atresia (BA) is a progressive fibro-inflammatory obliterative cholangiopathy that is the most common surgical cause of neonatal cholestasis (NC) and the leading indication for pediatric liver transplantation. Early and accurate diagnosis is critical, as outcomes of Kasai hepatic portoenterostomy are significantly better when performed within 60 days of life. Hepatic subcapsular flow (HSF) on color Doppler ultrasonography (USG) has been proposed as a non-invasive diagnostic marker for BA, but its performance has not been adequately validated in diverse clinical settings. Objectives This study aimed to evaluate the diagnostic accuracy of HSF on color Doppler USG as the primary index test and percutaneous liver biopsy and hepatobiliary scintigraphy as comparator index tests for the diagnosis of BA in infants with NC, using per-operative cholangiogram (POC) as the reference standard. Methods This was a pilot cross-sectional diagnostic accuracy study conducted at a single tertiary care center between August 2018 and July 2021, reported in accordance with the Standards for Reporting Diagnostic Accuracy Studies (STARD) 2015 guidelines. Infants up to six months of age with conjugated hyperbilirubinemia were enrolled consecutively. All participants underwent fasting abdominal USG with color Doppler assessment of HSF, hepatobiliary scintigraphy (hepatobiliary iminodiacetic acid (HIDA) scan), and USG-guided percutaneous liver biopsy (evaluated using the Chen scoring system, threshold ≥8). The reference standard was POC. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall diagnostic accuracy were calculated for each index test against POC. Results Thirty-four patients were enrolled (22 males, 12 females; mean age 3.09 ± 1.46 months). BA was confirmed in 25 (73.5%) patients on POC. HSF was detected in eight patients (23.5%), all of whom had confirmed BA: sensitivity 32.0%, specificity 100%, PPV 100%, NPV 34.6%, and overall accuracy 50.0%. HIDA scintigraphy demonstrated sensitivity of 100%, specificity of 22.2%, PPV of 78.1%, NPV of 100%, and overall accuracy of 79.4%. Liver biopsy (Chen score ≥8): sensitivity 100%, specificity 22.2%, PPV 78.1%, NPV 100%, and accuracy 79.4%. The mean Chen score was 9.08 in BA versus 8.78 in non-BA patients (p = 0.207). Liver biopsy suspicion of BA correlated significantly with the POC reference standard (p = 0.014). Conclusion HSF on color Doppler USG demonstrated high specificity but low sensitivity for the diagnosis of BA in this cohort, limiting its utility as a stand-alone screening tool. Liver biopsy demonstrated the most clinically informative overall diagnostic performance. With the exception of HSF sensitivity, all reported diagnostic accuracy estimates in this pilot study should be regarded as exploratory, given limited statistical power. These findings should be interpreted cautiously because of the small sample size, late presentation profile, and operator variability. Larger prospective multicenter studies are required to validate the diagnostic utility of HSF.