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T58 vs T71.222A

T58 (Toxic effect of carbon monoxide) compared with T71.222A (Asphyxiation due to being trapped in a car trunk, intentional self-harm, initial encounter), from the official CMS tabular data.

Summary

These codes should not be reported together because T71.222A’s tabular entry lists T58 under Excludes1.

Official rule
What is different?

The conditions named and billing status.T58 is “Toxic effect of carbon monoxide”; T71.222A is “Asphyxiation due to being trapped in a car trunk, intentional self-harm, initial encounter”. T58 is a non-billable header; T71.222A is billable.

Registry fact

Can these codes be reported together?

No.T71.222A’s entry carries an Excludes1 note covering T58: “asphyxia from carbon monoxide (T58.-)”. 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.T71.222A’s tabular entry: “asphyxia from carbon monoxide (T58.-)”. The note covers T58.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes2 relationship?

None.Neither entry carries an Excludes2 note that names the other code.

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.T58 is a non-billable header, but T71.222A 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

T71.222A
Asphyxiation due to being trapped in a car trunk, intentional self-harm, initial encounter
↔
T58
Toxic effect of carbon monoxide

What we found

No — do not report together.T71.222A carries an Excludes1 note covering T58: “asphyxia from carbon monoxide (T58.-)”

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

T58Toxic effect of carbon monoxideT71.222AAsphyxiation due to being trapped in a car trunk, intentional self-harm, initial encounter
Billing statusNon-billable header

Report instead: T58.01XA, T58.01XD, T58.01XS, T58.02XA, T58.02XD

Billable
ClassificationS00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)
DefinitionToxic effect of carbon monoxide is a non-billable ICD-10-CM category code (T58).Asphyxiation due to being trapped in a car trunk, intentional self-harm, initial encounter is a billable ICD-10-CM diagnosis code (T71.222A).
7th characterThe appropriate 7th character is to be added to each code from category T58The appropriate 7th character is to be added to each code from category T71
Includes
asphyxiation from carbon monoxide
toxic effect of carbon monoxide from all sources
—
Excludes1
contact with and (suspected) exposure to toxic substances (Z77.-)
acute respiratory distress (syndrome) (J80)
anoxia due to high altitude (T70.2)
asphyxia NOS (R09.01)
asphyxia from carbon monoxide (T58.-)
asphyxia from inhalation of food or foreign body (T17.-)
asphyxia from other gases, fumes and vapors (T59.-)
respiratory distress (syndrome) in newborn (P22.-)
Use additional code
code(s):
for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70)
personal history of foreign body fully removed (Z87.821)
—
Code also—
, if applicable, place of occurrence, such as:
highway rest stop (Y92.523)
school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
service areas as the place of occurrence of the external cause (Y92.52-)
single-family non-institutional (private) house as the place of occurrence of the external cause (Y92.01-)
transport vehicle as the place of occurrence of the external cause (Y92.81-)

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 (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources