[Agenesia of the canal of Arantius. A case report].

Looking for the etiology of hydramnios which became symptomatic at 21 weeks' gestation ultrasonography revealed a hepatic vascular abnormality without other symptoms. The suspected diagnosis was agenesis of the ductus venosus with creation of a high grade arteriovenous shunt between the umbilical vein and the inferior vena cava. Agenesis of the ductus venosus may be one expression of the different possible systemic-portal-umbilical abnormalities. Physiological consequences vary according to the type of substitutive anastomoses.