A catheter is a tube inserted into a patient’s cavity and used to deliver medicine, liquids, or food to the body. It can also be used to get rid of body fluids such as urine. The classification of a catheter is based on whether they are external or subcutaneous. There are vascular access devices or intravenous catheters, urinary catheters, and chest drainage tubes. The application of an external catheter consists of implantation in the superior vena cava, the large vein located near the heart. On the other hand, the subcutaneous catheters are introduced completely under the skin and are also inserted into a large vein.