Antenatally detected cystic biliary atresia: differential diagnoses of a double bubble

The ‘double bubble’ sign on antenatal ultrasound is often associated with duodenal atresia although there are numerous causes. We present a case of cystic biliary atresia presenting with a “double bubble” at 36-weeks gestation. Postnatal ultrasound and MRCP confirmed a cystic lesion at the porta hepatis, mandating early laparotomy and a successful Kasai portoenterostomy. Although diagnosis of such lesions may be imprecise antenatally, awareness and detection does allow early postnatal investigation and management, which is vital to optimise outcome. This case highlights the need to be mindful of other important anomalies that can give this appearance and that may require early intervention.