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R40.21 ICD-10-CM Code: Coma scale, eyes open

Billing Status: NO. This is a clinician non-billable / parent hierarchy grouping in the ICD-10-CM system.

Coding at a Glance

7th character
Required — characters 0 · 1 · 2 · 3 · 4
Tabular directives
4 Excludes1 · 1 Excludes2 · 3 code-first instructions

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for R40.21 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on R40.21 itself; “inherited from” names the category or block whose note applies here.

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Source: inherited from R40

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from R40-R46

Code First

Underlying conditions that must be sequenced before this code.

  • any associated:
  • fracture of skull (S02.-)
  • intracranial injury (S06.-)

Source: inherited from R40.2

7th Character Guide

"The following appropriate 7th character is to be added to subcategory R40.21-:"

  • 0 — unspecified time
  • 1 — in the field [EMT or ambulance]
  • 2 — at arrival to emergency department
  • 3 — at hospital admission
  • 4 — 24 hours or more after hospital admission

Variant codes in this family

R40.2110, R40.2111, R40.2112, R40.2113, R40.2114, R40.2120, R40.2121, R40.2122

Character meanings are CMS's official 7th-character extensions for this family, as carried in each variant code's official description; variant codes are registry rows. The explanation of how the encounter character is assigned is MedCoder editorial, distinct from the official content above it.

Coder workflow for R40.21

MedCoder structured workflow — derived from this code’s own official record

Before you code R40.21

  1. R40.21 is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

    ReviewR40.211, R40.212, R40.213, R40.214

    See the relationships section · Guide: How to choose an ICD-10-CM code →

  2. Check whether an established diagnosis that explains this sign or symptom is documented. If one is, review whether the documented diagnosis changes the coding pathway: a symptom that is integral to a confirmed diagnosis is not reported separately, while one not routinely associated with it may be. Signs and symptoms are reported when no definitive diagnosis is established (Guidelines I.B.4, I.B.5, I.B.6, I.C.18.b).

    Guide: Symptom code vs confirmed diagnosis →

  3. A 7th character is required in this family. Confirm the documentation supports the character assigned — its meaning in this family is defined in the official instruction. R40.21 is not valid without one. The official 7th-character definitions for this family are quoted in the guide.

    See the 7th Character Guide

  4. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with R40.21. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support one of the more specific codes beneath R40.21?
    Yes → Select that code and continue the checks below on its own page.
    No → R40.21 cannot be reported as written; query for the specificity its subcategory needs.

    ReviewR40.211, R40.212, R40.213, R40.214

  2. Is an established diagnosis that explains this sign or symptom documented?
    Yes → Review whether the documented diagnosis changes the coding pathway: a symptom integral to it is not reported separately.
    No → Continue — the sign or symptom code stands when no definitive diagnosis is established.
  3. Does the documentation support a condition named in R40.21’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewP91.5, K72, E15

  4. Is the underlying (etiologic) condition the Code First note names documented?
    Yes → Sequence the underlying condition first, then R40.21.
    No → Continue; do not add an underlying condition the record does not document.

    ReviewS02, S06

  5. Does the documentation support one of this family’s 7th-character values?
    Yes → Assign the matching 7th character; the variant codes are in the 7th Character Guide.
    No → The code is invalid without its 7th character — query for the missing element.

Consider R40.21. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
7th-character basis
The documented element this family’s 7th character records (see the official definitions in the 7th Character Guide).
Open or closed; displaced or nondisplaced
Defaults apply when the record is silent: closed, and displaced (Guidelines I.C.19.c).
The underlying (etiologic) condition
Named in the Code First note; sequenced before this code when documented (Guidelines I.A.13).

Official instructions as workflow

  • Excludes1 — check before selecting R40.21(4 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with R40.21: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareP91.5, K72, E15

    See the official tabular notes · Guidelines I.A.12.a

  • Excludes2 — not part of R40.21(1 note)

    Coding workflow: The conditions named in this note are not included in R40.21. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    See the official tabular notes · Guidelines I.A.12.b

  • Code First — sequencing check(3 notes)

    Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before R40.21. Do not add an underlying condition the record does not document.

    ReviewS02, S06

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The sign or symptom is documented, and the same record establishes a diagnosis that routinely includes it.

Coding question: Is R40.21 reported in addition to the diagnosis?

Path: Review the documented diagnosis and whether the classification treats this finding as integral to it.

Reason: Signs and symptoms integral to a confirmed diagnosis are not coded separately; those not routinely associated with it may be reported when present (Guidelines I.B.5, I.B.6, I.C.18.b).

Documentation: Both the condition R40.21 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewP91.5, K72, E15

Documentation: The underlying condition the Code First note names is documented alongside this condition.

Coding question: How are the two sequenced?

Path: Review the Code First note.

Reason: The underlying condition is sequenced first and the manifestation follows (Guidelines I.A.13).

ReviewS02, S06

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Coma scale, eyes open is a non-billable ICD-10-CM category code (R40.21). A more specific billable subcode must be selected for claims submission.

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Chapter 18: Symptoms, signs, and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)

1) Coma Scale The coma scale codes (R40.21- to R40.24-) can be used in conjunction with traumatic brain injury codes. These codes cannot be used with code R40.2A, Nontraumatic coma due to underlying condition. They are primarily for use by trauma registries, but they may be used in any setting where this information is collected. The coma scale codes should be sequenced after the diagnosis code(s).

Decision Points

The directives on this code's own record, as a pre-claim checklist.

  1. A 7th character applies in this family. Confirm the documented encounter matches the character assigned. See the official 7th-character definitions and this code’s variants
  2. Sequencing: 3 Code First instructions — the underlying condition is sequenced before this code when present. See the Code First notes
  3. 4 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes
  4. 1 Excludes2 entry — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name R40.21 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 5 Excludes1 notes: R40.0 — Somnolence (via R40.2.-), R40.1 — Stupor (via R40.2.-), R40.2A — Nontraumatic coma due to underlying condition, R41.82 — Altered mental status, unspecified (via R40.-), R55 — Syncope and collapse (via R40.2.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 2 Use Additional Code instructions: T65.85 — Toxic effect of medetomidine (via R40.-), T67.0 — Heatstroke and sunstroke (via R40.-).

These codes instruct coders to additionally report this code when it applies.

Contextual Map

Every relationship of R40.21 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run R40.21 with these 7 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Use Additional Code instructions

Nearest codes (40)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Common coding questions

Can R40.21 be billed directly?

No. R40.21 (Coma scale, eyes open) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Does R40.21 require a 7th character?

Yes. The following appropriate 7th character is to be added to subcategory R40.21-:; 0: unspecified time; 1: in the field [EMT or ambulance]; 2: at arrival to emergency department; 3: at hospital admission; 4: 24 hours or more after hospital admission.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "R40.21 — Coma scale, eyes open." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/r40.21-coma-scale-eyes-open

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Coma scale, eyes open

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to R40.21 in its code family, with their registry titles.

View all codes in the R40 family