Complete descriptions of all CPT modifiers are found in __________.

The full descriptions of all CPT modifiers are found in Appendix A of the Current Procedural Terminology (CPT) codebook. This appendix compiles a comprehensive list of modifiers, which are two-digit codes that provide additional information about the services and procedures performed. Modifiers can indicate that a service was altered in some way but not changed in its core definition or code.

Appendix B typically contains information related to changes in the CPT codes over time, such as additions, deletions, and revisions made from previous editions. Appendix C primarily includes a summary of the guidelines for certain categories of codes and not detailed explanations of modifiers. Appendix D relates to the summary of the modifiers specific to anesthesia services.

Thus, for anyone needing to understand the specific uses and meanings of the modifiers relevant to CPT coding, Appendix A serves as the essential reference.