Inferior Vena Cava Agenesis: An Underrated Cause of Deep Venous Thrombosis.

The absence of the inferior vena cava (IVC) is a rare abnormality reported in less than 1% of the population. The condition is usually the result of defects during embryogenesis. The collateral veins are enlarged with agenesis IVC, enabling blood transport to the superior vena cava.