Abernethy malformation connecting to a supradiaphragmatic vein may be missed due to their rarity or lack of awareness. Embryological reasons explain the involvement of the left superior caval vein in these connections.

Abernethy malformations manifest as hepatopulmonary syndrome, pulmonary vasculopathy, or encephalopathy. A novel intervention in a child with portosystemic shunt and inferior caval vein hypoplasia led to complete normalisation of hypoxia and relief of obstruction in the inferior caval vein. Embryological explanations of venous anomalies may indicate that inferior caval vein anomalies are frequent but under-recognised in patients with Abernethy malformation.

Agenesis of the venous duct is a rare congenital anomaly resulting in abnormal drainage of the umbilical vein into the foetal venous circulation. The clinical presentation and prognosis is variable, and may depend on the specific drainage pathways of the umbilical vein. We present two foetuses with agenesis of the venous duct, both associated with a postnatal portosystemic shunt, but with markedly different postnatal clinical courses. We also review all previously reported cases to better characterise this foetal disorder and the prognosis.