Current Procedural Terminology codes are used to provide a uniform description of medical, diagnostic and surgical services. Each procedure a physician may perform has its own five-digit code, used for record-keeping and billing purposes. Physicians use them to submit claims to insurance companies who reimburse based on the codes.
CPT codes work with International Classification of Diseases codes, or ICD codes. These codes are assigned when a patient is diagnosed with a condition. The pairing of these codes helps insurers look for billing mistakes. For instance, if a bill contains a CPT code describing a procedure involving a patient's stomach while the ICD code indicates a lung condition, the insurer can reject the charge or ask for clarification.