Azygos continuation of the inferior vena cava: sonographic demonstration of the renal artery ventral to the azygos vein as a clue to diagnosis.

OBJECTIVE: The purpose of this report is to describe the relationship between the renal artery and the azygos vein in patients with congenital infrahepatic interruption of the inferior vena cava with azygos continuation. CONCLUSION: Using abdominal sonography, we showed that in patients with interruption of the inferior vena cava with azygos continuation, the renal artery is ventral to the azygos vein. Because this malformation is frequently associated with cardiac and situs anomalies, awareness of the anatomic relationship between the renal artery and the azygos vein can aid in diagnosis and may substitute for more expensive and invasive diagnostic procedures.