CT images in a portal venous phase showing a distension and non-enhancement along the infrarenal IVC, common iliacs, external iliacs and femoral veins. There is also a thrombus extension noted into right renal vein. As an anatomical variant, the hepatic segment of the IVC is absent and the IVC continues into the azygous venous system; the hepatic veins join and drain directly into the right atrium. Mild perivascular fat stranding is observed along the thrombosed vessels. the remainder exam is unremarkable.