Is T79.A9 a billable ICD-10-CM code?

No. T79.A9 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does T79.A9 sit in the tabular list?

Injury, poisoning and certain other consequences of external causes (S00-T88), in the block Certain early complications of trauma (T79).

What cannot be coded together with T79.A9?

T79.A9 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above T79.A9 (T79.A) and apply to it just the same.

T79.A9

T79.A9 — Traumatic compartment syndrome of other sites

Non-billable headerICD-10-CM

T79.A9 is a non-billable header ICD-10-CM code for traumatic compartment syndrome of other sites. It cannot be billed on its own: choose one of the more specific child codes below. This code also requires a 7th character before it is complete.

This code requires a 7th character

The appropriate 7th character is to be added to each code from category T79

A: initial encounter
D: subsequent encounter
S: sequela

Excludes1 inherited from the categories above T79.A9

These are not written on T79.A9, but they bind it: a note on a category applies to every code beneath it. Billing T79.A9 with anything listed here is a denial.

Written on T79.A — Traumatic compartment syndrome

fibromyalgia (M79.7)
nontraumatic compartment syndrome (M79.A-)

Excludes2 inherited from the categories above T79.A9

Also inherited, and the opposite of Excludes1: these conditions are not part of T79.A9, but a patient can have both, so you may code both.

Written on T79.A — Traumatic compartment syndrome

traumatic ischemic infarction of muscle (T79.6)

Written on T79 — Certain early complications of trauma, not elsewhere classified

acute respiratory distress syndrome (J80)
complications occurring during or following medical procedures (T80-T88)
complications of surgical and medical care NEC (T80-T88)
newborn respiratory distress syndrome (P22.0)

Risk adjustment

T79.A9 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

How T79.A9 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to T79.A9.

Compartment syndrome›specified site NEC
Syndrome›compartment›specified site NEC

Code history

T79.A9 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.

Code to one of these instead T79.A9

3 child codes. Green means billable.

Related codes at this level

Codes that share T79.A. If T79.A9 is not quite right, the correct code is usually one of these.

Questions about T79.A9

Is T79.A9 a billable ICD-10-CM code?: No. T79.A9 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does T79.A9 sit in the tabular list?: Injury, poisoning and certain other consequences of external causes (S00-T88), in the block Certain early complications of trauma (T79).
What cannot be coded together with T79.A9?: T79.A9 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above T79.A9 (T79.A) and apply to it just the same.