What indicates that a procedure or service has been altered without changing its definition or code?

Modifiers are used in the Healthcare Common Procedure Coding System (HCPCS) to indicate that a procedure or service has been altered in some way without changing its definition or the code itself. They provide additional information about the service provided, offering context that can affect billing and reimbursement, while maintaining the same basic procedure code.

For instance, a modifier might indicate that a procedure was performed on a different limb than the one usually expected, or that it was done in a more complex manner. This ability to modify codes without reassigning entirely new codes helps categorize the nuances of patient care and ensures accurate documentation and claims processing.

Other choices, such as additional numeric codes, explanatory notes, and sub-coding, serve different purposes in medical coding and documentation. Additional numeric codes may represent completely different or additional services, explanatory notes provide clarification but do not alter code meaning, and sub-coding typically refers to more specific codes rather than modifying existing ones. Thus, these do not fulfill the criteria of indicating an alteration to a procedure or service without changing its core definition or code.