Methodology & sources
Every code, description, clinical note, index term, drug entry, and DRG association on this site is sourced directly from official, public-domain files published by the Centers for Medicare & Medicaid Services (CMS) and the National Center for Health Statistics (NCHS) — the federal agencies responsible for maintaining the ICD-10-CM classification and MS-DRG system used in the United States. This site is an independent, commercially operated project and is not affiliated with, endorsed by, sponsored by, or approved by CMS, HHS, NCHS, or any other government agency.
Primary data source
The core dataset is parsed directly from the official ICD-10-CM Tabular List XML, the authoritative machine-readable file CMS/NCHS release each fiscal year. It encodes the full chapter → section → category → code hierarchy along with every Includes, Excludes1, Excludes2, Code First, Use Additional Code, and 7th-character note exactly as published.
Index, drug table, and coding changes
The Index to Diseases and Injuries and Table of Drugs and Chemicals sections are parsed from the corresponding official CMS/NCHS XML files. The Changes section reflects the official annual addenda file listing codes added, revised, and deleted for the current fiscal year.
ICD-9 crosswalk
ICD-9-CM equivalents shown on code pages come from the CMS General Equivalence Mappings (GEMs), the last official crosswalk published before ICD-9-CM was retired. These mappings are approximate, not one-to-one equivalents, and should be reviewed by a coding professional before use in billing — see our Disclaimer.
MS-DRG associations
DRG pages and the DRG associations shown on code pages are parsed from the official CMS MS-DRG Definitions Manual. This site surfaces the principal-diagnosis code lists published for each DRG; it is not a full DRG grouper and does not account for procedures, complications/comorbidities (CC/MCC), discharge status, or payer-specific edits that affect real-world DRG assignment.
Original content
Chapter and category overviews, the plain-language explanations of each note type, and the Guidelines section are written independently based on (not copied from) the official CMS/NCHS ICD-10-CM Official Guidelines for Coding and Reporting — they represent our own explanation of the rules, not a reproduction of the source document.
Site design
This site's navigation, page structure, visual design, and editorial content were built independently. They are not modeled on, and do not copy, the layout or presentation of any other ICD-10-CM reference site.
Update cadence
CMS/NCHS release updated ICD-10-CM and MS-DRG files annually, effective October 1 each year, with occasional mid-year addenda. We re-run our full data pipeline against each new release and rebuild the site accordingly. Current data reflects the fiscal year noted at the top of each code, DRG, and crosswalk page.
Source citations
- ICD-10-CM Tabular List, Index to Diseases and Injuries, Table of Drugs and Chemicals — CMS/NCHS, FY2026
- ICD-10-CM Addenda (annual code changes) — CMS/NCHS, FY2026
- ICD-10-CM Official Guidelines for Coding and Reporting — CMS/NCHS (used as background reference for original commentary, not reproduced)
- General Equivalence Mappings (ICD-9-CM ↔ ICD-10-CM) — CMS/CDC, 2018 (final official release)
- MS-DRG Definitions Manual — CMS, current fiscal year
This site is independently operated and is not affiliated with, endorsed by, sponsored by, or approved by CMS, HHS, NCHS, AHA, or any other government agency or third party.