MCMCB Pro
S06.821A

S06.821AInjury of left internal carotid artery, intracranial portion, not elsewhere classified with loss of consciousness of 30 minutes or less, initial encounter

Billable / specific codeICD-10-CMleft

S06.821A is a billable, specific ICD-10-CM code for injury of left internal carotid artery, intracranial portion, not elsewhere classified with loss of consciousness of 30 minutes or less, 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 S06, except as noted below

A
initial encounter
D
subsequent encounter
S
sequela

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

  • Injury of left internal carotid artery, intracranial portion, not elsewhere classified with brief loss of consciousness

Risk adjustment

S06.821A risk-adjusts. Under the CMS-HCC V28 model it maps to this category:

  • HCC 398 Major Head Injury with Loss of Consciousness < 1 Hour or Unspecified0.199 RAF

Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score.

Medicare coverage

S06.821A is named in 13 Medicare coverage policies 13 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

  • A54111Billing and Coding: Speech Language Pathology (SLP) Services: Communication Disorders
  • A56537Billing and Coding: Scanning Computerized Ophthalmic Diagnostic Imaging (SCODI)
  • A56612Billing and Coding: CT of the Head
  • A56631Billing and Coding: Thoracic Aortography and Carotid, Vertebral, and Subclavian Angiography

Related codes at this level

Codes that share S06.821. If S06.821A is not quite right, the correct code is usually one of these.

Questions about S06.821A

Is S06.821A a billable ICD-10-CM code?
Yes. S06.821A is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does S06.821A 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.