The inferior vena cava (IVC) is formed by the confluence of the common iliac veins, just anterior to the L5 vertebral body, and posterior to the right common iliac artery. As it courses superiorly towards the diaphragm, it lies to the right of the lumbar and thoracic vertebral bodies. It enters the thorax at T8, where the right crus of the diaphragm separates the IVC and aorta. In most individuals, there is a small segment of suprahepatic IVC, about 1 cm in length, between the liver and diaphragm, which is amenable to cross clamping.

The IVC receives four or five pairs of lumbar veins, the right gonadal vein, the renal veins, the right adrenal vein, the hepatic veins, and the phrenic veins. It is of practical importance to remember that all lumbar veins are below the renal veins and that between the renal veins and the hepatic veins, besides the right adrenal vein, there are no other venous branches. The left lumbar veins pass behind the abdominal aorta.

The confluence of the renal veins with the IVC lies posterior to the duodenum and the head of the pancreas.

The retrohepatic IVC is about 8–10 cm in length and is adhered to the posterior liver, helping to anchor the liver in place. In this liver “tunnel,” several accessory veins from the caudate lobe and right lobe drain directly into the IVC.

There are three major hepatic veins which drain the liver into the IVC. The extrahepatic portion of these veins is short, measuring about 0.5–1.5 cm in length. The right hepatic vein is the largest. In about 70% of individuals, the middle vein drains into the left hepatic vein to enter the IVC as a single vein.

The thoracic IVC is almost entirely in the pericardium.