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W16.321 vs W73.XXXA

W16.321 (Fall into other water striking bottom causing drowning and submersion) compared with W73.XXXA (Other specified cause of accidental non-transport drowning and submersion, initial encounter), from the official CMS tabular data.

Summary

These codes should not be reported together because W16.321’s tabular entry lists W73.XXXA under Excludes1.

Official rule
What is different?

The conditions named and billing status.W16.321 is “Fall into other water striking bottom causing drowning and submersion”; W73.XXXA is “Other specified cause of accidental non-transport drowning and submersion, initial encounter”. W16.321 is a non-billable header; W73.XXXA is billable.

Registry fact

Can these codes be reported together?

No.W16.321’s entry carries an Excludes1 note covering W73.XXXA: “drowning and submersion while in other water without fall (W73)”. 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.W16.321’s tabular entry: “drowning and submersion while in other water without fall (W73)”. The note covers W73.XXXA.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes2 relationship?

None.Neither entry carries an Excludes2 note that names the other code. W16.321 carries 4 Excludes2 notes and W73.XXXA carries 1 Excludes2 note 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.W16.321 is a non-billable header, but W73.XXXA 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

W16.321
Fall into other water striking bottom causing drowning and submersion
↔
W73.XXXA
Other specified cause of accidental non-transport drowning and submersion, initial encounter

What we found

No — do not report together.W16.321 carries an Excludes1 note covering W73.XXXA: “drowning and submersion while in other water without fall (W73)”

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

W16.321Fall into other water striking bottom causing drowning and submersionW73.XXXAOther specified cause of accidental non-transport drowning and submersion, initial encounter
Billing statusNon-billable header

Report instead: W16.321A, W16.321D, W16.321S

Billable
ClassificationV00-Y99 — External Causes of Morbidity (V00-Y99)V00-Y99 — External Causes of Morbidity (V00-Y99)
DefinitionFall into other water striking bottom causing drowning and submersion is a non-billable ICD-10-CM category code (W16.321).Other specified cause of accidental non-transport drowning and submersion, initial encounter is a billable ICD-10-CM diagnosis code (W73.XXXA).
7th characterThe appropriate 7th character is to be added to each code from category W16The appropriate 7th character is to be added to code W73
Includes—
Accidental drowning and submersion while in quenching tank
Accidental drowning and submersion while in reservoir
Excludes1
drowning and submersion while in other water without fall (W73)
accidental non-watercraft drowning and submersion not involving fall (W65-W74)
effects of air pressure from diving (W94.-)
fall into water from watercraft (V90-V94)
hitting an object or against bottom when falling from watercraft (V94.0)
assault involving a fall (Y01-Y02)
fall from animal (V80.-)
fall (in) (from) machinery (in operation) (W28-W31)
fall (in) (from) transport vehicle (V01-V99)
intentional self-harm involving a fall (X80-X81)
accidental drowning and submersion due to fall into other water (W16.311, W16.321, W16.331)
accidental drowning and submersion due to fall into water (W16.-)
accidental drowning and submersion due to water transport accident (V90.-, V92.-)
Excludes2
striking or hitting diving board (W21.4)
at risk for fall (history of fall) Z91.81
fall (in) (from) burning building (X00.-)
fall into fire (X00-X04, X08)
accidental drowning and submersion due to cataclysm (X34-X39)

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