The inferior vena cava (IVC), also known as the posterior vena cava, is the large vein that carries deoxygenated blood from the lower half of the body into the right atrium of the heart.
It is posterior to the abdominal cavity and runs alongside of the vertebral column on its right side (i.e., it is a retroperitoneal structure). It enters the right atrium at the posterior inferior aspect of the heart on the right side.
The IVC is formed by the joining of the left and right common iliac veins. It anastomoses with the azygos vein system and venous plexuses next to the spinal cord.
Because the IVC is not centrally located, there are some asymmetries in drainage patterns. The gonadal veins and suprarenal veins drain into the IVC on the right side, but into the renal vein on the left side, which in turn drains into the IVC. By contrast, all of the lumbar veins and hepatic veins usually drain directly into the IVC.