🧬 ICD-10 CM S06.309D — Unspecified Focal Traumatic Brain Injury With Loss Of Consciousness Of Unspecified Duration, Subsequent Encounter
Billable Code Confirmed
ICD-10 CM S06.309D is a complete 7-character code — S06.3 (focal TBI) + 0 (unspecified/no laterality or type specified) + 9 (LOC of unspecified duration) + D (subsequent encounter) — valid for claim submission with no further specificity required.¹
Non-Billable Parent Codes
S06.309 (Unspecified focal traumatic brain injury with LOC of unspecified duration) is a header missing the 7th-character encounter type. S06.30 (Unspecified focal traumatic brain injury) and S06.3 (Focal traumatic brain injury) are broader header categories that cannot be billed on their own.²
Clinical Context
The 5th/6th-character “09” combination signals a focal brain injury (contusion/laceration not localized to a documented cerebral hemisphere) with a confirmed loss of consciousness whose duration was never pinned down; the “D” 7th character means this is a follow-up/healing-phase encounter rather than the acute injury visit.
Code Classification
This is a diagnosis code (ICD-10-CM), not a procedure code — pair it with any performed procedure codes separately; it does not itself drive surgical DRG weighting.
🔍 Code Description
Focal traumatic brain injury describes localized cerebral contusion, laceration, or hemorrhage confined to a discrete area of brain tissue, as opposed to diffuse axonal injury. S06.309D applies when the provider could not localize the injury to a specific cerebral hemisphere (right, left) and could not document how long the patient’s loss of consciousness lasted — a common documentation gap when a patient is transferred from an outside facility, or when the trauma note focuses on stabilization rather than a precise LOC timeline.
The “D” 7th character distinguishes this from S06.309A (initial encounter, used during the acute hospitalization) and S06.309S (sequela, used once the focus of care shifts to a late effect such as post-traumatic seizures or cognitive impairment). A subsequent encounter is appropriate for visits after active treatment has already occurred — for example, a rehab-unit stay, a follow-up outpatient-to-inpatient conversion, or an unrelated readmission where the healing focal TBI is still being monitored.
🌳 Code Tree / Hierarchy
S06.30 [Unspecified focal traumatic brain injury] ❌ Non-billable
│
├── S06.300 [Without loss of consciousness] ❌ Non-billable
│ ├── S06.300A / S06.300D / S06.300S ✅ Billable
│
├── S06.301 [LOC 30 min or less] ❌ Non-billable
│
├── S06.307 [Death due to brain injury before regaining consciousness] ❌ Non-billable
│ └── S06.307A only [D/S do not apply — death-related 6th character] ✅ Billable
│
├── S06.309 [LOC of unspecified duration] ❌ Non-billable
│ │
│ ├── S06.309A [initial encounter] ✅ Billable
│ ├── S06.309D [subsequent encounter] ◀ THIS CODE ✅ Billable
│ └── S06.309S [sequela] ✅ Billable
│
└── S06.30A [LOC status unknown] ❌ Non-billableSpecificity Insight
Payers will deny a claim submitted with the header S06.309 — the 7th character is mandatory. If the injury is later localized to a hemisphere (e.g., right cerebrum), re-code to the matching S06.319D-family code rather than leaving it under the “unspecified” focal TBI subcategory.
Tip
Note that 7th characters D and S do not apply to the death-related 6th characters (7 and 8) anywhere in category S06 — those combinations only ever take an “A.” This is a frequent audit flag when a coder mistakenly appends “D” to a death-outcome code.
✅ Includes
Traumatic brain injury — S06.309D falls under the general “traumatic brain injury” inclusion note that applies across the entire S06 category.²
❌ Excludes
Excludes 1
Any condition classifiable to S06.4-S06.6 (epidural, subdural, or subarachnoid hemorrhage) is excluded here — if the hemorrhage is specifically epidural, subdural, or subarachnoid, code to that more specific hemorrhage subcategory instead of the general focal-TBI family. At the category level, S09.90 (Head injury NOS) is also excluded, since a documented focal injury is inherently more specific than an unqualified head injury.²
Danger
The most common Excludes1 error is defaulting to the general “focal traumatic brain injury, unspecified” code when the operative or imaging report actually identifies a specific hemorrhage type (epidural, subdural, subarachnoid) — always cross-check imaging/op notes before finalizing this subcategory.
Excludes 2
S06.1 (Focal cerebral edema) may be coded in addition to S06.309D when a patient has both a focal contusion/laceration and documented cerebral edema, since these represent distinct pathophysiologic processes that can coexist.
📋 Clinical Overview
Localization vs. Duration Specificity
Two separate axes drive S06.3-family code selection: the 5th character indicates which cerebral hemisphere (or “unspecified” location) is affected, while the 6th character indicates LOC duration and the 7th character indicates encounter phase.
| Feature | S06.309D | Related S06.309A | Related S06.300D |
|---|---|---|---|
| Hemisphere localized? | No (unspecified) | No (unspecified) | No (unspecified) |
| LOC duration | Unspecified | Unspecified | No LOC documented |
| Encounter phase | Subsequent (healing/follow-up) | Initial (active treatment) | Subsequent (healing/follow-up) |
Important
If S06.309D is being used as principal diagnosis on an acute inpatient claim, confirm whether the admission is genuinely for ongoing management of the healing focal TBI or whether a new acute finding (e.g., new contusion on repeat imaging) actually warrants an initial-encounter code instead.
Manifestations & Symptom Burden
During the subsequent-encounter phase, documentation often reflects persistent headache, cognitive slowing, irritability, or post-concussive-type symptoms rather than the acute presentation. New or worsening focal neurologic deficits at this stage should prompt a query, since that may represent a new bleed requiring an initial-encounter code.
Tip
“Subsequent encounter” reflects treatment phase, not symptom resolution — a patient coded S06.309D can still be significantly symptomatic during ongoing rehabilitation.
💰 HCC Risk Adjustment
Under the CMS-HCC V28 model fully phased in for payment year 2026, the major head-injury payment categories (HCC 397 and HCC 398) are populated by initial-encounter (“A” 7th-character) codes documenting acute LOC duration.³ Subsequent-encounter codes in this family are generally excluded from those payment HCCs, since the model captures acute health-event severity rather than the follow-up phase. Flag for independent verification against the current CMS-HCC V28 ICD-10-CM mapping file before relying on this for RAF calculations.
🏥 MS-DRG Assignment
| DRG | Title | CC/MCC Status |
|---|---|---|
| 083 | Traumatic Stupor & Coma, Coma <1 Hr | w MCC |
| 084 | Traumatic Stupor & Coma, Coma <1 Hr | w CC |
| 085 | Traumatic Stupor & Coma, Coma <1 Hr | w/o CC/MCC |
These DRGs are typically driven by an initial-encounter intracranial injury code as principal diagnosis; S06.309D as a subsequent-encounter code will rarely group here as principal diagnosis and more often functions as a secondary diagnosis, potentially supporting CC/MCC status on an unrelated admission. There is no diagnosis-specific NCD for S06.309D itself; coverage considerations attach to the procedures performed to monitor or manage the focal TBI (repeat neuroimaging, neurosurgical intervention if a delayed complication develops), which are subject to your MAC’s (Noridian JE/JF) local coverage determinations for medical necessity.⁴ Flag for live verification against the Medicare Coverage Database for the LCD applicable to whatever procedure is billed alongside this diagnosis.
🔗 Related ICD-10-CM Codes
Same subcategory family (S06.30 — Unspecified focal TBI): S06.300A, S06.300D, S06.300S (without LOC), S06.309A (initial encounter), S06.309S (sequela)
Other focal traumatic brain injury by laterality, subsequent encounter: S06.319D (right cerebrum, LOC unspecified duration), S06.329D (left cerebrum, LOC unspecified duration), S06.339D (cerebrum unspecified, LOC unspecified duration)
🛠️ Commonly Associated CPT Codes
- 70450 — CT head/brain without contrast. Standard follow-up imaging to assess resolution of the focal contusion during the healing phase.⁵
- 70460 — CT head/brain with contrast, used selectively when a delayed vascular complication is suspected.
- 70551 — MRI brain without contrast; more sensitive than CT for evaluating residual focal parenchymal injury during follow-up.
- 99231, 99232, 99233 — Subsequent hospital inpatient/observation care, reflecting ongoing daily management documented during a subsequent-encounter admission.
- 61154 — Burr hole(s) with evacuation of hematoma; billed if a delayed focal collection requires drainage during a later admission.
🏷️ Modifier Reference
| Modifier | Name | When to Apply |
|---|---|---|
| -25 | Significant, Separately Identifiable E/M | Apply when a significant, separately identifiable E/M service is performed the same day as a minor procedure related to monitoring the healing focal TBI. |
| -59 | Distinct Procedural Service | Apply when imaging or a minor procedure performed during the subsequent-encounter visit is distinct from another same-day bundled service. |
| -78 | Unplanned Return to OR | Apply if the patient requires an unplanned return to the operating room for a delayed complication of the focal injury during the same postoperative period. |
| -79 | Unrelated Procedure by Same Physician During Postop Period | Apply when a procedure unrelated to the focal TBI is performed by the same surgeon during a global period tied to a prior cranial procedure. |
NCCI Bundling Considerations
CT head/brain codes (70450, 70460, 70470) will bundle under NCCI edits when multiple contrast phases of the same study are billed on the same date; only the single most comprehensive code should be reported rather than stacking individual component codes.
🔬 ICD-10-PCS Crosswalk
00980ZZ— Reposition, dura mater, open approach — used if a subsequent-encounter admission involves surgical exploration related to the healing focal injury.00N03ZZ— Release, epidural space, open approach — applicable only if a delayed collection requires surgical decompression during the subsequent encounter. Flag for independent verification — exact PCS root operation depends on the specific procedure note.009030Z— Drainage of cerebral meninges, open approach — applicable if a delayed hematoma is drained.
💊 Coding Scenarios and Examples
Example 1
Clinical Scenario: A patient with a focal cerebral contusion sustained three weeks prior (LOC duration never documented at the outside facility) is admitted to inpatient rehab for continued cognitive rehabilitation, with no new acute finding on repeat imaging.
| Field | Code | Rationale |
|---|---|---|
| PDx | S06.309D | Subsequent encounter for ongoing management of the healing focal TBI with undocumented LOC duration. |
| CPT | 99232 | Moderate-complexity subsequent hospital care reflecting daily rehab-unit management. |
Tip
Confirm the admission is genuinely for continued management rather than a new acute event before finalizing this as principal diagnosis.
Example 2
Clinical Scenario: A patient readmitted three weeks after the original focal TBI develops a delayed focal hematoma requiring burr-hole drainage.
| Field | Code | Rationale |
|---|---|---|
| CPT | 61154 | Burr hole with evacuation of the delayed focal hematoma. |
| PDx | S06.309D | Subsequent-encounter code appropriate since this is ongoing management of the original injury, not a brand-new traumatic event. |
Tip
If imaging clearly identifies this as a new, unrelated traumatic bleed, an initial-encounter code would apply instead — confirm mechanism and timeline with the surgeon.
Example 3
Clinical Scenario: A follow-up outpatient-to-inpatient conversion visit for persistent headache and mild cognitive complaints three weeks post-focal TBI; repeat CT shows resolving contusion with no intervention needed.
| Field | Code | Rationale |
|---|---|---|
| PDx | S06.309D | Subsequent encounter for routine follow-up during the healing phase. |
| CPT | 70450 | Follow-up CT head without contrast to assess resolution of the focal injury. |
Tip
Sequela coding (S06.309S) would only apply once care shifts to treating a late effect (e.g., post-traumatic headache syndrome or cognitive impairment) rather than the acute/healing injury itself.
⚠️ Coding Pitfalls and Tips
- Pitfall 1: Reporting the non-billable header S06.309 without the 7th character; Tips: always confirm all three positions of the extension (hemisphere digit + duration digit + encounter letter) are present before finalizing the code.
- Pitfall 2: Appending “D” or “S” to a death-outcome 6th character (7 or 8); Tips: remember that S06 category notes restrict 7th characters D and S from applying to the death-related 6th characters — only “A” is valid there.
- Pitfall 3: Defaulting to S06.309D (unspecified location and duration) when the imaging report actually localizes the contusion to a hemisphere; Tips: review the radiology/op note, not just the current encounter note, before finalizing specificity.
- Pitfall 4: Confusing “subsequent encounter” with “resolved condition”; Tips: subsequent encounter reflects treatment phase, not symptom resolution.
- Pitfall 5: Assuming this code maps to an HCC category; Tips: verify the current-year V28 crosswalk file directly, since subsequent-encounter TBI codes are generally excluded from the major head-injury payment HCCs.
📚 Sources
1. Centers for Medicare & Medicaid Services and National Center for Health Statistics. *ICD-10-CM FY2026 Full Code List.* CMS; 2026. https://www.cms.gov/icd10m/ 2. AAPC/Coding Ahead. *S06.309 — Unspecified focal traumatic brain injury with loss of consciousness of unspecified duration.* 2026. https://www.codingahead.com/icd-10-s06-309/ 3. HCC Buddy. *CMS-HCC V28 Category 397/398 — Major Head Injury.* 2026. https://hccbuddy.com/hcc/v28/397 4. Noridian Healthcare Solutions. *Medicare Coverage Database — Local Coverage Determinations, JE/JF.* CMS; 2026. 5. CMS Physician Fee Schedule. *PPRRVU2026_Jan_QPP File.* CMS; January 2026.Sources listed above correspond to superscript citations throughout this note. Verify all Medicare payment figures against your current CMS PFS Lookup tool and applicable MAC LCD prior to claim submission. Please use the latest AAPC/AHIMA Coding Books to verify each code within this note.