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S04.20XA

S04.20XAInjury of trochlear nerve, unspecified side, initial encounter

Billable / specific codeICD-10-CMunspecified

S04.20XA is a billable, specific ICD-10-CM code for injury of trochlear nerve, unspecified side, initial encounter. It is valid for submission on a claim.

7th character "A" — initial encounter

The appropriate 7th character is to be added to each code from category S04

A
initial encounter
D
subsequent encounter
S
sequela

Risk adjustment

S04.20XA 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.

Medicare coverage

S04.20XA is named in 1 Medicare coverage policy 1 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

  • A57637Billing and Coding: Visual Field Examination

Related codes at this level

Codes that share S04.20. If S04.20XA is not quite right, the correct code is usually one of these.

Questions about S04.20XA

Is S04.20XA a billable ICD-10-CM code?
Yes. S04.20XA is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does S04.20XA sit in the tabular list?
Injury, poisoning and certain other consequences of external causes (S00-T88), in the block Injuries to the head (S00-S09).
ICD-10-CMFY2026-Apr· effective April 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release — see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.