An IV cannula is a small, flexible tube inserted into a vein, typically in the hand or arm, to provide continuous or intermittent access to the bloodstream. It is used to administer fluids, medications, blood products, or to withdraw blood samples. The cannula is inserted with the help of a sharp needle, which is removed once the plastic catheter is in place inside the vein. It comes in different sizes (gauges), color-coded to indicate their diameter and flow rate, allowing for use in various clinical situations from trauma and surgery to routine fluid administration.