Book excerpt: ICD-10-CM 2021: The Complete Official Codebook provides the entire updated code set for diagnostic coding, organized to make the challenge of accurate coding easier. This codebook is the cornerstone for establishing medical necessity, determining coverage and ensuring appropriate reimbursement. Each of the 21 chapters in the Tabular List of Diseases and Injuries is organized to provide quick and simple navigation to facilitate accurate coding. The book also contains supplementary appendixes including a coding tutorial, pharmacology listings, a list of valid three-character codes and additional information on Z-codes for long-term drug use and Z-codes that can only be used as a principal diagnosis. Official coding guidelines for 2021 are bound into this codebook. FEATURES AND BENEFITS Full list of code changes. Quickly see the complete list of new, revised, and deleted codes affecting the FY 2021 codes, including a conversion table and code changes by specialty. QPP symbol in the tabular section. The symbol identifies diagnosis codes associated with Quality Payment Program (QPP) measures under MACRA. New and updated coding tips. Obtain insight into coding for physician and outpatient settings. New and updated definitions in the tabular listing. Assign codes with confidence based on illustrations and definitions designed to highlight key components of the disease process or injury and provide better understanding of complex diagnostic terms. Intuitive features and format. This edition includes full-color illustrations and visual alerts, including color-coding and symbols that identify coding notes and instructions, additional character requirements, codes associated with CMS hierarchical condition categories (HCC), Medicare Code Edits (MCEs), manifestation codes, other specified codes, and unspecified codes. Placeholder X. This icon alerts the coder to an important ICD-10-CM convention--the use of a "placeholder X" for three-, four- and five-character codes requiring a seventh character extension. Coding guideline explanations and examples. Detailed explanations and examples related to application of the ICD-10-CM chapter guidelines are provided at the beginning of each chapter in the tabular section. Muscle/tendon translation table. This table is used to determine muscle/tendon action (flexor, extensor, other), which is a component of codes for acquired conditions and injuries affecting the muscles and tendons Index to Diseases and Injuries. Shaded guides to show indent levels for subentries. Appendices. Supplement your coding knowledge with information on proper coding practices, risk adjustment coding, pharmacology, and Z codes.