2027 ICD-10-CM Diagnosis Code T79.1XXAFat embolism (traumatic), initial encounter
ICD-10-CM Codes›S00–T88›T79›T79
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 267
- 7th Character A — Initial Encounter
- Not Chronic
T79.1XXA is a billable ICD-10-CM diagnosis code for fat embolism (traumatic), initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 175 through 176, 791, 793, 963 through 965. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 64 closely related codes. Coders also document this condition as early complication of trauma. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified injury.
For Medicare Advantage risk adjustment, T79.1XXA maps to CMS-HCC Category 267 (Deep Vein Thrombosis and Pulmonary Embolism) under the V28 model, adding a risk factor of about 0.294 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
T79.1XXA maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Early complication of trauma
- Fat embolism
- Fat embolism - obstetric
- Fat embolism as early complication of trauma
- Fulminant fat embolism syndrome
- Obstetric pulmonary embolism
- Pulmonary fat embolism
- Subacute pulmonary fat embolism
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Certain early complications of trauma, not elsewhere classified (T79). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027, published by CMS and the National Center for Health Statistics.
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to T79.1XXA: its own notes plus those printed at T79.1, T79, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify any retained foreign body, if applicable (Z18.-)
Notes
General instructions on how these codes are used.
- Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
- The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.
7th Character
Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.
- The appropriate 7th character is to be added to each code from category T79
- Ainitial encounter this code
- Dsubsequent encounter
- Ssequela
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name T79.1XXA, its category, or a range that includes it.
Excludes2 1
These codes carry an Excludes2 note naming T79.1XXA: its condition is not part of those codes, and both may be reported when the patient has both.
Code First 2
These codes say to code first a condition named in the note, and T79.1XXA is one of the conditions named.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Embolism, Fat
blocking of a blood vessel by fat deposits in the circulation. it is often seen after fractures of large bones or after administration of corticosteroids.
Convert T79.1XXA to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T79.1XXAOverview
What is the ICD-10 code for fat embolism (traumatic), initial encounter?
The ICD-10-CM code for fat embolism (traumatic), initial encounter is T79.1XXA (sometimes written as T791XXA). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is T79.1XXA (Fat embolism (traumatic)) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report fat embolism (traumatic), initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character A in T79.1XXA mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for fat embolism (traumatic), such as an emergency visit or first evaluation.
What MS-DRG does T79.1XXA group to?
When fat embolism (traumatic), initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 175, 964, 965, 176, 963, with relative weights from 0.8061 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is T79.1XXA a CC or MCC?
CMS lists T79.1XXA as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 64 closely related codes in its exclusion list.
What HCC is T79.1XXA?
T79.1XXA (fat embolism (traumatic), initial encounter) maps to CMS-HCC Category 267 (Deep Vein Thrombosis and Pulmonary Embolism), commonly written as HCC 267, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 173 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does T79.1XXA risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, T79.1XXA adds a risk adjustment factor of about 0.294 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.245 to 0.568 depending on the payment segment). HCC 267 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 267 category page.
