Healthcare Diagnostic and Treatment Coding



  • Level II codes maintained by CMS
  • alphanumeric medical diagnostic codes
  • primarily non-physician services: ambulance, prosthetics
  • items, supplies and non-physician services not covered by CPT-4 codes (Level I)
  • one letter in the range A to V followed by 4 digits

“The Healthcare Common Procedure Coding System (HCPCS, often pronounced by its acronym as “hick picks”) is a set of health care procedure codes based on the American Medical Association‘s Current Procedural Terminology (CPT).” –


ICD-9 and ICD-10 – International Classification of Disease

  • Sponsored by WHO
  • Codes up to 6 characters
  • 3 character minimum
  • if there are more specific sub-codes, the 3-digit code will be in boldface followed by subsequent numbers
  • Diagnosis-based


RVS – Relative Value System codes

  • Created by insurers
  • Evolved into CPT


CPT-4 – Current Procedural Terminology (CPT)

  • Owned by AMA
  • Equals HCPCS Level 1
  • 5-digit codes plus modifiers

“The Current Procedural Terminology (CPT) code set is a medical code set maintained by the American Medical Association through the CPT Editorial Panel … CPT coding is similar to ICD-9 and ICD-10 coding, except that it identifies the services rendered rather than the diagnosis on the claim. ICD code sets also contain procedure codes but these are only used in the inpatient setting.” –


A system of Medicare diagnosis groupings using medical codes to define Medicare compensation.


National Codes

  • Created for CMS
  • for billing procedures and supplies for Medicare patients
  • Widely used by insurers