Flags of sovereign nations should not be flown on the same pole as the United States Flag but from separate poles. The United Nations Headquarters Building in New York City, where the U.N. Flag holds the most prominent position, is the only U.S. location exempted from this provision.
Inferior vena cava. The inferior vena cava (or IVC) (Latin: vena, vein, cavus, hollow) is a large vein that carries deoxygenated blood from the lower and middle body into the right atrium of the heart. Its walls are rigid and has valves so the blood does not flow down via gravity.
An inferior vena cava filter is a type of vascular filter, a medical device that is implanted by interventional radiologists or vascular surgeons into the inferior vena cava to presumably prevent life-threatening pulmonary emboli. Their effectiveness and safety profile is not well established, and in general, they are only recommended in some high-risk scenarios. They are not intended to be a replacement for medical management of venous thromboembolism. However, in cases where patients are at hi