Is W21.4 a billable ICD-10-CM code?

No. W21.4 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does W21.4 sit in the tabular list?

External causes of morbidity (V00-Y99), in the block Exposure to inanimate mechanical forces (W20-W49).

What cannot be coded together with W21.4?

W21.4 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above W21.4 (W21) and apply to it just the same.

W21.4

W21.4 — Striking against diving board

Non-billable headerICD-10-CM

W21.4 is a non-billable header ICD-10-CM code for striking against diving board. It cannot be billed on its own: choose one of the more specific child codes below. This code also requires a 7th character before it is complete.

This code requires a 7th character

The appropriate 7th character is to be added to each code from category W21

A: initial encounter
D: subsequent encounter
S: sequela

Use additional code

Add a secondary code to capture the detail described below.

code for subsequent falling into water, if applicable (W16.-)

Excludes1 inherited from the categories above W21.4

These are not written on W21.4, but they bind it: a note on a category applies to every code beneath it. Billing W21.4 with anything listed here is a denial.

Written on W21 — Striking against or struck by sports equipment

assault with sports equipment (Y08.0-)
striking against or struck by sports equipment with subsequent fall (W18.01)

Other codes that can never be billed with W21.4

These codes carry an Excludes1 note pointing at W21.4. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading W21.4 alone.

W20Struck by thrown, projected or falling object
W20.8Other cause of strike by thrown, projected or falling object
W20.8XXAOther cause of strike by thrown, projected or falling object, initial encounter
W20.8XXDOther cause of strike by thrown, projected or falling object, subsequent encounter
W20.8XXSOther cause of strike by thrown, projected or falling object, sequela

Risk adjustment

W21.4 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

How W21.4 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to W21.4.

Striking against›diving board(swimming-pool)
Fall, falling›into›water›hitting diving board

Code history

W21.4 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.

Code to one of these instead W21.4

3 child codes. Green means billable.

Related codes at this level

Codes that share W21. If W21.4 is not quite right, the correct code is usually one of these.

Questions about W21.4

Is W21.4 a billable ICD-10-CM code?: No. W21.4 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does W21.4 sit in the tabular list?: External causes of morbidity (V00-Y99), in the block Exposure to inanimate mechanical forces (W20-W49).
What cannot be coded together with W21.4?: W21.4 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above W21.4 (W21) and apply to it just the same.