ICD-10 code S06.813S: Right internal carotid artery sequela

Key takeaways

ICD-10 code S06.813S covers an injury of the right internal carotid artery, intracranial portion. The sixth character adds loss of consciousness of 1 hour to 5 hours 59 minutes.

S06.813S is a vascular injury code. The generic bucket for an unnamed intracranial injury is S06.89, and its matching sequela code is S06.893S.

The seventh character S applies once the carotid injury itself is closed out and only its residual effects remain.

Sequence the residual deficit first, then S06.813S. Skip the I69 codes, which exclude sequelae of traumatic intracranial injury.

Practice management software like Pabau keeps the vessel, the healed status, and the residual condition in one record a coder can read.

A coder skims the S06 block, spots “loss of consciousness” in the descriptor, and reaches for the nearest generic head-injury code. That single habit turns S06.813S, a specific right internal carotid artery injury, into the wrong claim.

Yet the two codes read almost the same on the page. One names a damaged artery inside the skull. The other is a catch-all for intracranial injuries nobody has pinned down yet. Submit the wrong one, and the payer sees a diagnosis the chart cannot support.

Here’s how to read the descriptor correctly, sequence it against the residual condition, and keep the claim clean from the first submission.

ICD-10 code S06.813S names an injured right carotid artery inside the skull

ICD-10 code S06.813S covers an injury to the right internal carotid artery, in the portion that runs inside the skull. The sixth character adds loss of consciousness of 1 hour to 5 hours 59 minutes. The S at the end marks the sequela stage.

Here is the official description in full.

Injury of right internal carotid artery, intracranial portion, not elsewhere classified with loss of consciousness of 1 hour to 5 hours 59 minutes, sequela.

It is a valid, billable ICD-10-CM code for HIPAA-covered transactions. The Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics maintain it on the annual fiscal year cycle. That descriptor has held steady across FY2024, FY2025, and FY2026.

Every field on S06.813S in one place

Where the carotid stops being a neck vessel and becomes an intracranial one

The dividing line is the skull base. Once the internal carotid artery enters the carotid canal and travels inside the cranium, an injury to it belongs in S06.8.

Below that point, the same vessel is a neck injury under S15.0-, where sequela codes such as S15.029S live.

The Alphabetic Index spells the split out. The entry Injury, carotid artery (common) (external) (internal, extracranial) points to S15.00-. Its subentry internal, intracranial points to S06.8-. From there the Tabular List splits by side, sending the right artery to S06.81- and the left to S06.82-.

The left-side family runs the same way. Codes like S06.821S cover the left artery at the shorter loss of consciousness durations.

S06.81 carries no Excludes1 note of its own in the FY2026 Tabular List. The instructions that govern it sit one level up at the S06 category, plus two reciprocal exclusions filed elsewhere. Those six notes are worth keeping on a sticky note.

The sixth character carries the loss of consciousness band, and the severity story with it

The 3 in S06.813 is the loss of consciousness field, and it means 1 hour to 5 hours 59 minutes. Nothing wider. A documented 45-minute loss of consciousness belongs to S06.812-. Six hours moves the claim to S06.814-.

Match the duration in the record to the stem before you think about the seventh character.

Those severity labels come from the VA/DoD loss of consciousness criterion. Mild runs to 30 minutes, moderate covers anything over 30 minutes and under 24 hours, and severe starts past 24 hours.

That puts S06.813- and S06.814- in the same moderate band, even though S06.814- sits higher in the list. Severity is a clinical descriptor that sits outside the code itself. If the record meets a higher band on imaging or Glasgow Coma Scale, the higher band wins.

One more thing about that sixth character. It describes the patient, not the vessel. A right intracranial carotid injury with no loss of consciousness is still an S06.81- code, just with a 0 in the sixth position.

Those duration bands repeat elsewhere in S06 too, so a diffuse injury code like S06.2X4A reads the same way in its sixth character.

The seventh character S says the injury is finished and the damage is not

Reach for S06.813S when the carotid injury itself is no longer being treated and the patient still carries something it caused. That is the entire test. A dissection that has healed or been stented, in a patient who still has a weak arm, is a sequela encounter.

The line between D and S moves on clinical status, not on the calendar. A patient still on aspirin with a pseudoaneurysm under angiographic surveillance is a D encounter, even two years out. A patient discharged from vascular follow-up who comes in for speech therapy is an S encounter, even at three months.

Two limits catch people out. The seventh characters D and S never attach to sixth characters 7 or 8, because those codes describe a patient who died before regaining consciousness. And when nothing residual remains at all, the right code is Z87.820, personal history of traumatic brain injury, rather than a sequela code.

Six levels of ICD-10-CM sit behind S06.813S

Read the chain from the top down and you can see how much specificity each character buys. It runs from the chapter block to the code you submit.

• S00-S09: injuries to the head (block)
• S06: intracranial injury (category)
• S06.8: other specified intracranial injuries (subcategory)
• S06.81: injury of right internal carotid artery, intracranial portion, not elsewhere classified
• S06.813: the same injury with loss of consciousness of 1 hour to 5 hours 59 minutes
• S06.813S: that code with the sequela seventh character

S06.8 holds four subcategories, and this is where most of the confusion starts. Two of them are carotid codes split by side. One is a blast injury code. The last one is the catch-all that S06.813S gets mistaken for.

So if your documentation says other specified intracranial injury and never names a vessel, S06.893S is your code. The two look nearly identical in a code list, and they describe different injuries. Reviewers spot the mismatch fast, because a carotid code with no vascular finding in the note has nothing to support it.

Three encounters where S06.813S is the right code

Traumatic injury to the intracranial carotid is uncommon. Blunt cerebrovascular injury turns up in roughly 1% to 2% of trauma admissions, and considerably more often in patients with severe head injury. A cervical spine fracture such as S12.120B is one of the findings that prompts screening for it.

The sequela encounters that follow tend to look like one of these three. A neurological exam checklist helps you capture the residual findings each one turns on.

Stroke deficits after a healed carotid dissection

A driver sustains a right internal carotid artery dissection in a collision, with two hours of documented unconsciousness. Angiography a year later shows the vessel healed. He still has left-sided weakness and slurred speech from the infarct the dissection threw. The neurologist codes the hemiparesis and the dysarthria first, then adds S06.813S to name the cause.

Follow-up after a repaired carotid-cavernous fistula

A skull base fracture can tear the carotid where it passes through the cavernous sinus. The result is a carotid-cavernous fistula, reported in a small fraction of closed head injuries and usually treated with endovascular coiling.

Once the fistula is closed and the vessel injury is signed off, the encounter type changes. A patient may still have a sixth nerve palsy and reduced vision on that side. Those findings lead the claim, with S06.813S behind them.

Rehabilitation visits with a documented carotid injury behind them

Therapy encounters are where the sequela code earns its keep. The note codes the functional deficit as the reason for the visit. S06.813S rides along so the payer can see the injury it came from.

Practices running a physical therapy EMR should check that it carries a secondary diagnosis onto every visit, not only the initial evaluation. The same check applies in speech therapy software when dysarthria is the billed deficit.

Sequence the residual condition first, and leave the I69 codes alone

Section I.C.19 of the ICD-10-CM Official Guidelines for Coding and Reporting sets the order. The residual condition goes first as the principal or first-listed diagnosis. S06.813S follows it as an additional code. Flipping that pair is the most common sequela error there is.

The subtler trap catches experienced coders. A traumatic carotid injury that caused a stroke does not get an I69 code. Category I69 covers sequelae of cerebrovascular disease, and its Excludes1 note names sequelae of traumatic intracranial injury (S06.-) outright. So the residual hemiplegia is G81.-, never I69.35-.

G81 confirms it from the other direction. Its own Excludes1 pushes out hemiplegia due to sequela of cerebrovascular disease, which is precisely what makes G81 the correct home for a traumatic cause. Aphasia follows the same pattern: R47.01 after trauma, and the I69 series only after cerebrovascular disease.

Here is how the diagnosis list looks on a follow-up claim for the driver above.

Run this checklist before you submit an S06.813S claim

Most S06.813S rejections trace back to the note rather than the code. Work through these seven items before the claim leaves the building.

• Laterality. The record names the right internal carotid artery. A left-sided injury is S06.823S.
• Location. The note places the injury in the intracranial portion. An extracranial carotid injury is S15.0-.
• Duration. The documented loss of consciousness falls between 1 hour and 5 hours 59 minutes.
• Status. The note says the carotid injury has healed or been repaired, in those words.
• Residual. The current condition is named, sequenced first, and tied to the injury in writing.
• External cause. If you report one, give it the S seventh character. Leave place of occurrence and activity codes off, because those belong to the initial encounter.
• Companion codes. Add the skull fracture (S02.-) or open wound (S01.-) when the record documents one.

On the claim form itself, the residual condition takes the first diagnosis position and S06.813S goes in the next. Every service line should point at the residual condition as the reason for the visit, with S06.813S supporting it.

Pointing a therapy line at S06.813S alone is a quick route to a medical necessity review. The sequela code explains the history, not today’s treatment.

The mistakes that get S06.813S claims sent back

Six errors account for most of the rejections. Each one has a clean fix.

• Treating S06.813S as a general TBI code. With no vessel documented, the code is S06.893S. Same loss of consciousness band, different injury.
• Using D for an injury that is already settled. D means the carotid injury is still being managed. Once vascular follow-up closes, move to S.
• Adding an I69 stroke sequela code. I69 excludes sequelae of traumatic intracranial injury. Use G81.-, R47.-, or whichever deficit code fits.
• Listing S06.813S first. The residual condition takes the first position every time. S06.813S is the additional code.
• Reporting a concussion alongside it. The Excludes1 at S06.0X sends you to the specified intracranial injury. Report one code, not both.
• Letting laterality slip. Right and left carotid codes differ by a single digit, so a transcription error turns S06.813S into S06.823S.

Related codes worth keeping open alongside S06.813S

Carotid sequela encounters rarely need one code. Keep this shortlist within reach, because most claims pull from two or three rows of it.

CMS and NCHS review these codes every fiscal year. Check the current CMS code descriptions file or the AAPC Codify lookup before you rely on any of these on a live claim. Instructional notes move between years more often than descriptors do.

How Pabau keeps carotid sequela documentation claim-ready

Coding a sequela encounter well is a documentation job before it is a coding job. The note has to carry five facts: the vessel, the side, the loss of consciousness duration, the healed status, and the residual condition. Chase those across a paper chart and a separate billing system, and one of them goes missing.

Practice management software like Pabau keeps them together. Structured medical records hold the injury history and the current findings on the same patient file. A coder reads the full picture without emailing the neurologist.

Custom intake and consent forms can carry a short sequela block that prompts for vessel status and residual deficit at every follow-up. Pabau Scribe, our AI scribe, drafts the note from the consultation, so the causal sentence gets written while the detail is still fresh.

On the billing side, claims management submits insurer claims and validates the billing fields first, things like membership numbers and authorization codes. It does not sequence diagnosis codes or check seventh characters, so the ICD-10 call stays with your coder.

What it clears is the other kind of rejection, the claim that was coded perfectly and bounced on an insurer field.

Keep sequela notes and insurer claims in one place

Pabau holds the injury history, the residual findings, and insurer claim submission on one patient record. Your coders get the detail they need, and your billing team stops chasing fields across two systems.

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Conclusion

S06.813S rewards coders who read the descriptor all the way to the end. The vessel and the side are doing the real work here, and the loss of consciousness band is only the sixth character. Get either wrong and you have billed a different injury on the same claim form.

So build the check into the workflow instead of trusting memory. Ask whether the note names a right intracranial carotid injury, and whether unconsciousness ran from one to nearly six hours. Then ask whether the vessel is closed out and a deficit remains.

With all four answers on the page, S06.813S belongs on the claim behind that deficit. If one is missing, a different code does.

Practices that see these encounters regularly get further by fixing the note than by buying a better code lookup. Book a demo to see how Pabau keeps injury history, residual findings, and insurer claims on a single patient record.

Continue your research

Need a structured way to record residual neurological findings? Neurological exam checklist gives you a field-by-field exam record you can attach to every sequela follow-up.

Coding the neck portion of the same vessel? S15.029S covers the carotid injury that sits below the skull base, where S06.8 stops applying.

Billing the anesthesia for an endovascular repair? CPT 01926 walks through the anesthesia code for therapeutic interventional radiology work.

Recording the support a patient needs at home? Caregiver note template gives you a simple format for logging day-to-day help with a lasting deficit.

Releasing injury records to an insurer or attorney? Notice of privacy practices sets out how you tell patients when their records can be disclosed.

Frequently asked questions