W31.9 — Contact with unspecified machinery
W31.9 is a non-billable header ICD-10-CM code for contact with unspecified machinery. 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 W31
- A
- initial encounter
- D
- subsequent encounter
- S
- sequela
Inclusion terms
Alternative wordings a physician may use in the chart for this same code.
- Contact with machinery NOS
Excludes1 inherited from the categories above W31.9
These are not written on W31.9, but they bind it: a note on a category applies to every code beneath it. Billing W31.9 with anything listed here is a denial.
Other codes that can never be billed with W31.9
These codes carry an Excludes1 note pointing at W31.9. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading W31.9 alone.
Risk adjustment
W31.9 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 W31.9 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 W31.9.
- Cut, cutting›machine NEC
- Contact›with›machine, machinery
Code history
W31.9 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 W31.9
3 child codes. Green means billable.
Related codes at this level
Codes that share W31. If W31.9 is not quite right, the correct code is usually one of these.
Questions about W31.9
- Is W31.9 a billable ICD-10-CM code?
- No. W31.9 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
- Where does W31.9 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 W31.9?
- W31.9 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 W31.9 (W31) and apply to it just the same.