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M84.374A vs S42

M84.374A (Stress fracture, right foot, initial encounter for fracture) compared with S42 (Fracture of shoulder and upper arm), from the official CMS tabular data.

Summary

These codes should not be reported together because M84.374A’s tabular entry lists S42 under Excludes1.

Official rule
What is different?

The conditions named, billing status and chapter.M84.374A is “Stress fracture, right foot, initial encounter for fracture”; S42 is “Fracture of shoulder and upper arm”. S42 is a non-billable header; M84.374A is billable. M84.374A sits in M00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99); S42 in S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88).

Registry fact

Can these codes be reported together?

No.M84.374A’s entry carries an Excludes1 note covering S42: “traumatic fracture (S12.-, S22.-, S32.-, S42.-, S52.-, S62.-, S72.-, S82.-, S92.-)”. Both may be reported only when the documentation shows the two conditions are unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes1 relationship?

Yes.M84.374A’s tabular entry: “traumatic fracture (S12.-, S22.-, S32.-, S42.-, S52.-, S62.-, S72.-, S82.-, S92.-)”. The note covers S42.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes2 relationship?

None.Neither entry carries an Excludes2 note that names the other code. M84.374A carries 3 Excludes2 notes and S42 carries 5 Excludes2 notes covering other codes; the side-by-side table quotes them.

Official rule

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

One is a header.S42 is a non-billable header, but M84.374A is not one of its subdivisions.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Conflict

Excludes1 conflict

M84.374A
Stress fracture, right foot, initial encounter for fracture
↔
S42
Fracture of shoulder and upper arm

What we found

No — do not report together.M84.374A carries an Excludes1 note covering S42: “traumatic fracture (S12.-, S22.-, S32.-, S42.-, S52.-, S62.-, S72.-, S82.-, S92.-)”

Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

What to review

Report one of the two. Both may be reported only when the documentation shows the two conditions are unrelated to each other.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes1 note means the two conditions cannot occur together, so the pair should not be reported for the same encounter. The sole exception is when the conditions are documented as unrelated to each other.

Source / rule

CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a

Official guidance behind these answers

  • Section I.A.12.a — Excludes1 · applies to: Excludes1

    A type 1 Excludes note is a pure excludes note. It means “NOT CODED HERE!” An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition. An exception to the Excludes1 definition is the circumstance when the two conditions are unrelated to each other. If it is not clear whether the two conditions involving an Excludes1 note are related or not, query the provider. For example, code F45.8, Other somatoform disorders, has an Excludes1 note for "sleep related teeth grinding (G47.63)," because "teeth grinding" is an inclusion term under F45.8. Only one of these two codes should be assigned for teeth grinding. However psychogenic dysmenorrhea is also an inclusion term under F45.8, and a patient could have both this condition and sleep related teeth grinding. In this case, the two conditions are clearly unrelated to each other, and so it would be appropriate to report F45.8 and G47.63 together.

    ICD-10-CM Official Guidelines FY2026

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

M84.374AStress fracture, right foot, initial encounter for fractureS42Fracture of shoulder and upper arm
Billing statusBillableNon-billable header

Report instead: S42.001A, S42.001B, S42.001D, S42.001G, S42.001K

ClassificationM00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99)S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)
DefinitionStress fracture, right foot, initial encounter for fracture is a billable ICD-10-CM diagnosis code (M84.374A).Fracture of shoulder and upper arm is a non-billable ICD-10-CM category code (S42).
7th characterThe appropriate 7th character is to be added to each code from subcategory M84.3:The appropriate 7th character is to be added to all codes from category S42
Includes—
injuries of axilla
injuries of scapular region
Excludes1
pathological fracture NOS (M84.4.-)
pathological fracture due to osteoporosis (M80.-)
traumatic fracture (S12.-, S22.-, S32.-, S42.-, S52.-, S62.-, S72.-, S82.-, S92.-)
traumatic amputation of shoulder and upper arm (S48.-)
Excludes2
personal history of (healed) stress (fatigue) fracture (Z87.312)
stress fracture of vertebra (M48.4-)
traumatic fracture of bone-see fracture, by site
periprosthetic fracture around internal prosthetic shoulder joint (M97.3)
burns and corrosions (T20-T32)
frostbite (T33-T34)
injuries of elbow (S50-S59)
insect bite or sting, venomous (T63.4)
Use additional code
external cause code(s) to identify the cause of the stress fracture
—

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on.

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Derived from the official CMS ICD-10-CM tabular data (FY2026). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources