Agenesis of the venous duct: Two cases of extrahepatic drainage of the umbilical vein and extrahepatic portosystemic shunt with a review of the literature

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.