It is the lower, or inferior, part of the vena cava—a large vein also made up of the superior vena cava that carries blood from the head, neck, arms, and chest in the upper body to the heart.

Inferior vena cava filters are often used for prophylaxis in patients deemed to be a high risk for pulmonary embolism (e.g. bariatric surgery in the super-obese), although whether or not this ...