ICD-10-CM: Structure & Conventions

1. Alphabetic Index — find the condition by its main term (e.g. 'Fracture', 'Diabetes', 'Pain'), then subterms (site, type). It points you to a code. 2. Tabular List — the codes in order, organized into 21 chapters by body system or condition type (e.g. Chapter 4 Endocrine E00–E89, Chapter 9 Circulatory I00–I99, Chapter 19 Injury S00–T88).

The golden rule: NEVER code from the Index alone. Always verify the code in the Tabular List, where the instructional notes and full code are.