T79.A21A — Traumatic compartment syndrome of right lower extremity, initial encounter
Is T79.A21A billable?
Yes — T79.A21A is billable for FY2027. T79.A21A is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. T79.A21A may be submitted for encounters from October 1, 2026 through September 30, 2027.
T79.A21A at a glance
| Code | T79.A21A |
|---|---|
| Description | Traumatic compartment syndrome of right lower extremity, 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 T79.A21A?
In T79.A21A, the 7th character A means initial encounter. The 7th character is required for T79.A21A to be a valid, complete code.
Same condition, different episode of care — switch the 7th character:
Which MS-DRGs does T79.A21A group to?
T79.A21A sits in MDC 21 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 922Other Injury, Poisoning and Toxic Effect Diagnoses with MCCmedical
- 923Other Injury, Poisoning and Toxic Effect Diagnoses without MCCmedical
As a secondary diagnosis, T79.A21A is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG.
How is T79.A21A listed in the Alphabetic Index?
The Alphabetic Index lists these routes under T79.A2, the nearest indexed parent of T79.A21A. Use them to find the family, then select the specific code.
- Compartment syndrome › lower extremity (deep) (posterior) (traumatic)
- Syndrome › compartment › lower extremity
Excludes1 — never code together — inherited from T79.A
The conditions below can never be reported together with T79.A21A on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Use additional code — inherited from Chapter 19
Report an additional code alongside T79.A21A to fully describe the condition. T79.A21A 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 T79.A21A, but a patient may have both at the same time. When documentation supports it, T79.A21A and the excluded code may both be reported.
Excludes2 — not included here — inherited from T79
The conditions below are not part of T79.A21A, but a patient may have both at the same time. When documentation supports it, T79.A21A and the excluded code may both be reported.
Excludes2 — not included here — inherited from T79.A
The conditions below are not part of T79.A21A, but a patient may have both at the same time. When documentation supports it, T79.A21A and the excluded code may both be reported.
- traumatic ischemic infarction of muscle (T79.6)
How long has T79.A21A existed?
T79.A21A 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.