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M84.331 ICD-10-CM Code: Stress fracture, right ulna

Compare with another code for M84.331Check this code on a claim

Billing Status: NO. This is a non-billable ICD-10-CM code: report a more specific billable code beneath it.

Coding at a Glance

7th character
Required — see the character table on this page
Tabular directives
3 Excludes1 · 3 Excludes2 · 1 use-additional code

Not billable · FY2027A non-billable heading in the tabular list: report a more specific code beneath it.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too; the Instructions section marks which is which.

Use additional codeReport with this code when documented
  • external cause code(s) to identify the cause of the stress fracture
Excludes1Never report with this code
Excludes2Not included here; may be reported together
  • personal history of (healed) stress (fatigue) fracture (Z87.312)
  • stress fracture of vertebra (M48.4-)
  • traumatic fracture of bone-see fracture, by site

Where it sits Source: CMS/NCHS

Under:Chapter 13: Diseases of the Musculoskeletal System and Connective TissueM80-M94 Osteopathies and chondropathiesM80-M85 Disorders of bone density and structureM84 Disorder of continuity of boneM84.3 Stress fractureM84.33 Stress fracture, ulna and radius

Codes under M84.331 (6)

  • M84.331AStress fracture, right ulna, initial encounter for fractureBillable
  • M84.331DStress fracture, right ulna, subsequent encounter for fracture with routine healingBillable
  • M84.331GStress fracture, right ulna, subsequent encounter for fracture with delayed healingBillable
  • M84.331KStress fracture, right ulna, subsequent encounter for fracture with nonunionBillable
  • M84.331PStress fracture, right ulna, subsequent encounter for fracture with malunionBillable
  • M84.331SStress fracture, right ulna, sequelaBillable

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for M84.331 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on M84.331 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 M84.3

Excludes2 — Not Included Here

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

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • external cause code(s) to identify the cause of the stress fracture

Source: inherited from M84.3

7th Character Guide

"The appropriate 7th character is to be added to each code from subcategory M84.3:"

  • A — initial encounter for fracture
  • D — subsequent encounter for fracture with routine healing
  • G — subsequent encounter for fracture with delayed healing
  • K — subsequent encounter for fracture with nonunion
  • P — subsequent encounter for fracture with malunion
  • S — sequela

How the encounter character is assigned. “Initial encounter” means the patient is receiving active treatment for the condition — it is not limited to the first visit, and a different or new provider giving active treatment still assigns it. “Subsequent encounter” covers care during the healing or recovery phase after active treatment. “Sequela” is for complications or conditions that arise as a direct result of the original condition.

ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.19.a (paraphrased by MedCoder).

Variant codes in this family

M84.331A, M84.331D, M84.331G, M84.331K, M84.331P, M84.331S

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 M84.331

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

Before you code M84.331

  1. M84.331 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).

    ReviewM84.331A, M84.331D, M84.331G, M84.331K, M84.331P, M84.331S

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

  2. A 7th character is required in this family. Confirm the documented encounter: initial (active treatment), subsequent (healing or recovery phase), or sequela. M84.331 is not valid without one. “Initial” means active treatment, not the first visit (Guidelines I.C.19.a).

    See the 7th Character Guide · Guide: 7th characters: initial, subsequent, sequela →

  3. Laterality is coded in this family. Confirm the side documented — right, left, or bilateral — and select the matching code (this page’s code: right). The unspecified-side code applies only when the record states no side. Laterality is assigned from the documented side; where a bilateral code exists and both sides are documented, it is used instead of two unilateral codes (Guidelines I.B.13).

    ReviewM84.332 · left

    Guide: Laterality coding →

  4. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with the code beneath M84.331. 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 M84.331?
    Yes → Select that code and continue the checks below on its own page.
    No → M84.331 cannot be reported as written. Where the codes beneath it include an unspecified code, that code applies when the record goes no further; otherwise query for the missing detail.

    ReviewM84.331A, M84.331D, M84.331G, M84.331K, M84.331P, M84.331S

  2. Does the documentation support a condition named in M84.331’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.

    ReviewM84.4, M80, S12, S22, S32, S42

  3. Is the side documented?
    Yes → Select the code for the documented side (or the bilateral code when both sides are documented and one exists).
    No → Use the unspecified-side code only when the record states no side; a query is the alternative.

    ReviewM84.332 · left

  4. Is the encounter phase documented — active treatment, healing or recovery, or a sequela?
    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.

Report the code beneath M84.331 that the documentation supports, not M84.331 itself. Then work the Use Additional Code note, and confirm that code is valid for the date of service on its own page.

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).
Laterality
Right, left or bilateral as documented; unspecified only when the record states no side (Guidelines I.B.13).
Encounter type
Active treatment, healing or recovery phase, or sequela — the basis of the 7th character (Guidelines I.C.19.a).
Open or closed; displaced or nondisplaced
Defaults apply when the record is silent: closed, and displaced (Guidelines I.C.19.c).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

  • Excludes1 — check before selecting M84.331(3 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with M84.331: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareM84.4, M80, S12, S22, S32, S42

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

  • Excludes2 — not part of M84.331(3 notes)

    Coding workflow: The conditions named in this note are not included in M84.331. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareZ87.312, M48.4

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

  • Use Additional Code — after identifying M84.331(1 note)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with M84.331 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    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: Both the condition M84.331 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).

ReviewM84.4, M80, S12, S22, S32, S42

Documentation: The patient returns during the healing or recovery phase after active treatment of the same condition.

Coding question: Which 7th character applies?

Path: Review the official 7th-character definitions for this family in the 7th Character Guide.

Reason: “Initial encounter” means active treatment, not the first visit; care during recovery takes “subsequent encounter”, and a complication arising from the original condition takes “sequela” (Guidelines I.C.19.a).

Documentation: The record documents the condition on one side only.

Coding question: Which code in this family applies?

Path: Select the sibling code for the documented side.

Reason: Laterality is assigned from the documented side; the unspecified-side code is for records that state no side (Guidelines I.B.13).

ReviewM84.332 · left

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.

Don’t confuse M84.331 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of M84.331 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • M84.4— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of pathological fracture NOS moves the case to M84.4; the two are not reported together unless documented as unrelated.

    Full comparison: M84.331 vs M84.4 →

  • M80— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of pathological fracture due to osteoporosis moves the case to M80; the two are not reported together unless documented as unrelated.

    Full comparison: M84.331 vs M80 →

  • S12— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of traumatic fracture moves the case to S12; the two are not reported together unless documented as unrelated.

    Full comparison: M84.331 vs S12 →

  • S22— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of traumatic fracture moves the case to S22; the two are not reported together unless documented as unrelated.

    Full comparison: M84.331 vs S22 →

  • S32— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of traumatic fracture moves the case to S32; the two are not reported together unless documented as unrelated.

    Full comparison: M84.331 vs S32 →

  • S42— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of traumatic fracture moves the case to S42; the two are not reported together unless documented as unrelated.

    Full comparison: M84.331 vs S42 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Stress fracture, right ulna is a non-billable ICD-10-CM category code (M84.331). 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.

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. Laterality is coded in this family. Confirm the documented side matches the code — the opposite-side siblings are in the relationships section. See the opposite-side sibling codes
  3. 1 Use Additional Code instruction — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
  4. 3 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes
  5. 3 Excludes2 entries — 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-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name M84.331 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 1 Excludes1 note: M84.4 — Pathological fracture, not elsewhere classified (via M84.3.-).

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

Related Codes

Same condition, different side

Same title, differing only in which side of the body it names: right, left, bilateral or unspecified.

M84.332 — Stress fracture, left ulnaCompare M84.331 vs M84.332 →

Contextual Map

Every relationship of M84.331 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 M84.331 with this related code in Claim Check

Hierarchy

Referenced by Excludes1 notes

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

Relevant guides

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Common coding questions

MedCoder editorial

Can M84.331 be billed directly?

No. M84.331 (Stress fracture, right ulna) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Does M84.331 require a 7th character?

Yes. The appropriate 7th character is to be added to each code from subcategory M84.3:.

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 FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 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-derived 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 editorial 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.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

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. "M84.331 — Stress fracture, right ulna." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/m84.331-stress-fracture-right-ulna

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Stress fracture, right ulna

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, 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 M84.331 in its code family, with their registry titles.

View all codes in the M84 family