An IV cannula is a small, flexible tube inserted into a vein with the help of a needle. Once   the catheter is inside the vein, the needle is removed, leaving the tube in place. This tube allows medicines, fluids, or blood products to reach the bloodstream directly. An IV cannula helps doctors give treatment without repeatedly pricking the patient with a needle. It is widely used in emergency rooms, hospitals, surgical wards, and even in home care when IV therapy is required.