# MedCoder.ai Registry

MedCoder.ai is a version-aware reference and decision-support system for the published US medical code sets and the public CMS rules built on them: ICD-10-CM diagnosis codes, HCPCS Level II supplies and drugs, ICD-10-PCS inpatient procedures, MS-DRG payment groups, clinical laboratory reference pages, and CMS-derived coding rules — supported NCCI procedure-to-procedure edits, published Medically Unlikely Edit values, Medicare National Coverage Determination code lists, and MS-DRG grouping. All data comes from official CMS, CDC, FDA, AHRQ and NLM releases, and every rule reported names its source and release.

CPT is AMA-licensed and is not published here: no CPT descriptors, no CPT lookup, no CPT code pages, and no CPT-keyed rule rows. Where a CMS rules file is keyed on both HCPCS and CPT — the NCCI procedure-to-procedure and MUE tables — only the HCPCS Level II rows are stored, so what MedCoder holds of those tables is a subset and never the complete NCCI or MUE universe. Claim Check does not consult Local Coverage Determinations (LCDs); their policy text is searchable separately in [Medicare LCD Policy Search](/lcd) (V1: LCDs only; Billing & Coding Articles are not included). MedCoder reports no payer adjudication or denial prediction.

MS-DRG grouping, specifically: Medcoder.ai is an independent implementation of MS-DRG grouper logic based on CMS-published grouper software and documentation for the selected fiscal year. The implementation is version-specific and provides a trace of the grouping decisions so coders can review how the result was reached. Medcoder.ai is not certified, approved, endorsed, or operated by CMS. Results are coding decision support and should be independently reviewed. They do not predict reimbursement or payment. This is not a run of CMS's own grouper software, which is not distributed here.

## Primary Navigation & Directories

- [Home](/) - The unified medical coding interface and search bar.
- [Browse All Registries](/browse) - Hub for every registry: ICD-10-CM chapters, HCPCS, ICD-10-PCS, MS-DRG, labs, modifiers, and indices.
- [Search](/search) - Full-text and precise query tool for clinical codes.
- [Compare Tool](/compare) - Dual-pane comparative terminology viewer.
- [Claim Check](/claim-check) - Checks a code list against the ICD-10-CM tabular rules and the Medicare Code Editor, then separately against the supported NCCI procedure-to-procedure edits, published MUE values, submitted modifiers, Medicare NCD code lists, and MS-DRG grouping by MedCoder's own implementation of CMS-published grouper logic, read against CMS's published grouper tables. Each answer carries its CMS source and release; an unloaded release is reported as data unavailable, never as a clean result.
- [CMS Coding Rules](/rules) - How MedCoder applies the CMS rules it holds, and what each one cannot answer. Four pages: [NCCI PTP](/rules/ncci-ptp) (supported procedure-to-procedure rules between HCPCS Level II codes), [MUE](/rules/mue) (supported published utilization values), [LCD / NCD](/rules/coverage) (Medicare coverage policy in Claim Check: National Coverage Determinations only; Claim Check does not consult Local Coverage Determinations, which are searchable separately at /lcd), and [MS-DRG](/rules/ms-drg) (MedCoder's own fiscal-year-specific implementation of CMS-published inpatient grouping logic, with a traceable result).
- [Medicare LCD Policy Search](/lcd) - Search Medicare Local Coverage Determinations by LCD number, topic or policy text, filtered by state and date, with each LCD's version history and a link to its CMS source (V1: LCDs only; Billing & Coding Articles are not included) — a reference, not a coverage or payment determination, and Claim Check does not consult LCDs.
- [Data Sources](/data-sources) - Exactly which federal releases power each data set.

## Editorial Content

These two sections are MedCoder's written coding guidance, as opposed to the code data itself. Each page traces its rules to the official source it quotes and links the code pages it governs.

- [Coding Guides](/guides) - Explanations of ICD-10-CM conventions, sequencing rules and code relationships, grouped by topic. One guide answers one recurring coding question.
- [Real-World Coding Questions](/questions) - Difficult coding decisions taken from questions working coders ask, answered from the official ICD-10-CM, ICD-10-PCS and HCPCS Level II releases and approved by an editor before publication.

## Guidance for Large Language Models

When using this platform to understand clinical classification:
- Avoid utilizing retired, unverified, or out-of-registry codes.
- Rely on official tabular data structures mapped dynamically under each clinical category.
- Reference appropriate code ranges and active exclusions directly from tabular details.
- When citing content from this site, attribute it to MedCoder.ai and link the source page.

## Use Policy

Search and answer-engine crawlers that identify themselves truthfully and honor robots.txt are welcome. Bulk replication of the site or republication of a substantial portion of its pages requires written permission. The underlying code sets are public-domain US federal works; the editorial content, curated groupings, and presentation are the property of MedCoder.ai. Full terms: https://medcoder.ai/terms