Procedure:

Current Procedural Terminology (CPT) codes are copyrighted by the American Medical Association and are 5-position numeric codes, primarily representing physician services. CPT codes were developed in 1966 and are maintained annually by the American Medical Association (AMA).

The Health Care Common Procedure Coding System (HCPCS) is a collection of codes that represent procedures, supplies, products, and services. HCPCS codes were developed and maintained by CMS and are 5-position alphanumeric codes, representing primarily items and non-physician services that are not represented in CPT.

Diagnosis

The International Classification of Diseases (ICD) ninth revision, Clinical Modifications (ICD-9-CM), was implemented by the World Health Organization in 1975. Medicare Part B recognizes only ICD-9-CM diagnosis codes. The diagnosis should be coded to the highest level of specificity to reflect symptoms, signs, or other reasons for the visit/encounter billed.

Modifiers

Modifiers are 2-position codes used to show that a service or procedure performed has been altered by some specific circumstance, but not changed in its definition or code.