Biliary atresia with associated structural malformations in Canadian infants

Background: Biliary atresia (BA) is associated with extrahepatic congenital malformations in a minority of affected infants. The term commonly applied to this subgroup is 'BASM' for biliary atresia splenic malformation syndrome, as spleen abnormalities are prominent.

Aims and methods: To examine clinical outcome in Canadian BA patients with extrahepatic congenital malformations in the Canada-wide BA database of patients born between 1985 and 2002, and additionally, to recharacterized the syndrome. Patients had ≥1 of the following: a/polysplenia, abnormal abdominal situs, intestinal malrotation, abdominal vascular anomaly or congenital heart disease.

Results: Among 328 BA patients, 44 (13%) had associated congenital abnormalities. Intra-abdominal anomalies included polysplenia (n=25), abnormal abdominal situs (n=9), intestinal malrotation (n=19), portal vein anomaly (n=12), hepatic artery anomaly (n=3) and inferior vena cava interruption (n=20). Twenty-six patients had cardiac malformations including pulmonary stenosis (n=11), ventricular septal defect (n=10), atrial septal defect (n=7), total anomalous pulmonary venous return (n=3), double outlet right ventricle (n=3), tetralogy of Fallot (n=2), atrioventricular canal (n=2), dextrocardia (n=2), bicuspid aortic valve (n=2), hypoplastic left heart (n=1) and partial anomalous pulmonary venous return (n=1). Age at Kasai operation, performance of liver transplant, overall survival, post-Kasai native liver survival and transplant survival were comparable to isolated BA. Presence of polysplenia or complex cardiac disease did not reduce post-Kasai native liver survival. Three patients had ≥2 typical abnormalities without polysplenia: thus, splenic malformations are not essential to this BA subgroup. Hierarchical cluster analysis demonstrated characteristic abnormalities grouped in a multiplicity of combinations, consistent with a spectrum of defective lateralization.

Conclusion: We suggest that the acronym 'BASM' be redefined as 'biliary atresia structural malformation'.