Biliary Atresia Research Network Northeast

Inclusion Criteria: * Children with a healthcare encounter related to biliary atresia at a participating institution during the study period (January 1st, 2012 through December 31st, 2021) * Age 12 years and younger at the time of the qualifying encounter during the study period (encompassing patients born between January 2nd, 1999 through December 31st, 2021) * Diagnosis of biliary atresia, based on one of the following ICD-10 codes: * Q44.2 Atresia of bile ducts * Q44.3 Congenital stenosis and stricture of bile ducts * Q44.4 Disorders of the biliary tract with major complication or comorbidity * Q44.5 Other congenital malformations of the bile ducts * Q44.6 Disorders of the biliary tract without major complication or comorbidity Exclusion Criteria: * Patients aged 13 years old or older during the study period (i.e. those born before January 2nd, 1999) * Patients born and/or diagnosed with biliary atresia after the end of the study period (i.e. those born after December 31st, 2021) * No diagnosis of biliary atresia * History of biliary atresia without any episodes of care related to biliary atresia during the study period (e.g. a teenager with history of BA who underwent Kasai procedure as an infant and has no current issues related to their BA and is receiving care for an unrelated reason)