A guidewire for use in guiding the insertion of catheters bears a plurality of unique identifiers. These unique identifiers are used to choose the appropriate length of catheter to be inserted into the patient. Many of the steps of marking and measuring a guidewire and calculations utilizing the measurements are eliminated through use of this catheter bearing unique identifiers. In place of the detailed and error prone set of marking, measuring and calculating steps, a set of unique identifiers are printed or otherwise directly and immovable associated with the guidewire. A practitioner determines the stock length of catheter needed in a procedure merely by noting the placement of one unique identifier relative to a standard landmark.