Each CPT code is made up of five characters, which may be numeric or alphanumeric, depending on the category of the code. CPT codes are grouped into three categories. Category I codes pertain to most of the in and outpatient procedures performed by health care providers. Category II codes are used mainly for performance management, while category III codes describe emerging and trial procedures, services and technologies.
Category I codes are outlined in six parts: evaluation and management, anaesthesia, surgery, medicine, radiology, pathology and laboratory. Each section has defined code ranges. For instance, surgery is the largest section, with code ranges between 10021 and 69990.
Category II codes provide additional information to the Category I codes. They entail four digits followed by the character F. This category is classified into nine sections, including composite codes, patient management and patient history, among others. An example of a category II code is 0001F, which indicates heart failure assessed.
Category III codes help in the tracking of the efficiency of new medical techniques. These codes are five characters long, comprising of four digits and a terminal letter T. For example, 0123T represents the code for the fistulization of sclera for glaucoma through a ciliary body.