What CPT Medical Billing Codes are and their relationship to ICD-9 codes.

CPT stands for Current Procedural Terminology (4th edition) and is developed and maintained by the American Medical Association (AMA). It’s also referred to as CPT-4 to denote the 4th (or current) edition of the category I codes.

The CPT medical billing codes are copyrighted by the AMA which prevents free use and distribution of codes without their permission and authorization.

This 5 digit code describes medical services performed by a physician or healthcare provider. They are also used for surgical and diagnostic services. All major commercial and government insurance carriers require the use of CPT codes.

Three Categories of Codes
CPT medical billing codes are part of the HCPCS coding system. HCPCS consists of three levels:

  • Level I – CPT Medical coding maintained by the American Medical Association.
  • Level II – Alphanumeric codes used primarily to identify products, supplies, and services that are not included in the CPT codes, such as durable medical equipment, ambulance services, prosthetics, and supplies that are used outside of a providers office.
  • Level III – Known as local codes. These were developed by state Medicaid agencies, Medicare contractors, and private insurers to use in certain programs. Level III codes were discontinued in 2003.

The AMA revises the CPT codes annually. CPT codes are sometimes accompanied by modifiers. These are two digit codes associated with a CPT code which indicate the procedure has been altered. These modifiers are described in appendix A of the CPT publication.

CPT medical billing codes submitted on an insurance claim are associated with the ICD-9 code to show the procedure is medically necessary. There may be more than one ICD-9 code associated with each CPT code. The CMS 1500 form can accommodate up to 4 ICD-9 codes in box 21 of the form as referenced by the diagnosis pointer in box 24E.