Teenager with abdominal pain

CT of azygos continuation of the inferior vena cava
Coronal CT with contrast of the abdomen (below) shows interruption of the infrahepatic inferior vena cava which then communicates with the hemiazygos vein to the left of the spine which then via dilated azygos and hemiazygos venous collaterals alongside the vertebral body on the axial CT (above) ultimately drain into the superior vena cava.

The diagnosis was azygos continuation of the inferior vena cava.