Ultrasonic diagnosis of infrahepatic interruption of the inferior vena cava with azygos (hemiazygos) continuation.

Two patients with infrahepatic interruption of the inferior vena cava (IVC) with azygos (hemiazygos) continuation were examined ultrasonographically and the findings compared to seven normal studies. Pathognomonic ultrasonographic features of this anomaly are easily demonstrated and include absence of the IVC at the level of the liver and independent drainage of the confluence of hepatic veins into the right atrium. Conventional venography can now be replaced by ultrasonic examination to establish this diagnosis. The embryology, anatomy and clinical implications of this entity are discussed.