S15.099A — Other specified injury of unspecified carotid artery, initial encounter
Is S15.099A billable?
Yes, but S15.099A will trip a Medicare edit. S15.099A is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, CMS lists S15.099A under Medicare Code Editor edit 20, “Unspecified code” — meaning a code specifying laterality (right, left or bilateral) exists in the same family. On an inpatient claim this triggers the edit, because CMS holds that there are very limited circumstances in which laterality cannot be documented.
S15.099A at a glance
| Code | S15.099A |
|---|---|
| Description | Other specified injury of unspecified carotid artery, initial encounter |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
| 7th character "A" | initial encounter |
What does the 7th character "A" mean in S15.099A?
In S15.099A, the 7th character A means initial encounter. The 7th character is required for S15.099A to be a valid, complete code.
Same condition, different episode of care — switch the 7th character:
What Medicare edits apply to S15.099A?
The Medicare Code Editor screens inpatient claims before they are grouped. These edits name S15.099A directly.
A code specifying laterality (right, left or bilateral) exists in the same family. CMS holds that there are very limited circumstances in which laterality cannot be documented.
Which MS-DRGs does S15.099A group to?
S15.099A sits in MDC 15 and helps define the logic of 1 MS-DRG (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 791Prematurity with Major Problemsmedical
As a secondary diagnosis, S15.099A is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG.
How is S15.099A listed in the Alphabetic Index?
The Alphabetic Index lists these routes under S15.09, the nearest indexed parent of S15.099A. Use them to find the family, then select the specific code.
- Injury › blood vessel NEC › carotid artery › specified type NEC
Excludes1 — never code together — inherited from S15.0
The conditions below can never be reported together with S15.099A on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- injury of internal carotid artery, intracranial portion (S06.8)
Use additional code — inherited from Chapter 19
Report an additional code alongside S15.099A to fully describe the condition. S15.099A is sequenced first.
- code to identify any retained foreign body, if applicable (Z18.-)
Excludes2 — not included here — inherited from Chapter 19
The conditions below are not part of S15.099A, but a patient may have both at the same time. When documentation supports it, S15.099A and the excluded code may both be reported.
Excludes2 — not included here — inherited from S10-S19
The conditions below are not part of S15.099A, but a patient may have both at the same time. When documentation supports it, S15.099A and the excluded code may both be reported.
Code also — inherited from S15
Two codes may be needed to describe the condition fully. Whether S15.099A is sequenced first depends on the reason for the encounter.
- any associated open wound (S11.-)
How long has S15.099A existed?
S15.099A has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.