An intravenous (IV) catheter is a hollow tube that a doctor or nurse can thread through a vein to provide a route to administer medications and fluids directly into the bloodstream. IV catheters are usually placed in the hand, arm, or leg. Sometimes they are run into one of the internal or external jugular veins in the neck, or in a vein under the collar bone or in the chest. Some catheters are permanent and remain under the skin, while others are visible coming out of the skin, and usually remain in place for a fixed period of time.