The inferior vena cava is a large vein that carries deoxygenated blood from the lower and middle body into the right atrium of the heart. It is formed by the joining of the right and the left common iliac veins, usually at the level of the fifth lumbar vertebra.

The inferior vena cava is the lower (“inferior”) of the two venae cavae, the two large veins that carry deoxygenated blood from the body: the inferior vena cava carries blood from the lower half of the body whilst the superior vena cava carries blood from the upper half of the body.

It is a large retroperitoneal vein that lies posterior to the abdominal cavity and runs along the right side of the vertebral column. It enters the right atrium at the lower right, back side of the heart.