M79.A19 — Nontraumatic compartment syndrome of unspecified upper extremity
Is M79.A19 billable?
Yes, but M79.A19 will trip a Medicare edit. M79.A19 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, CMS lists M79.A19 under Medicare Code Editor edit 20, “Unspecified code” — meaning a code specifying laterality (right, left or bilateral) exists in the same family. On an inpatient claim this triggers the edit, because CMS holds that there are very limited circumstances in which laterality cannot be documented.
M79.A19 at a glance
| Code | M79.A19 |
|---|---|
| Description | Nontraumatic compartment syndrome of unspecified upper extremity |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
What Medicare edits apply to M79.A19?
The Medicare Code Editor screens inpatient claims before they are grouped. These edits name M79.A19 directly.
A code specifying laterality (right, left or bilateral) exists in the same family. CMS holds that there are very limited circumstances in which laterality cannot be documented.
Which MS-DRGs does M79.A19 group to?
M79.A19 sits in MDC 08 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.
- 557Tendonitis, Myositis and Bursitis with MCCmedical
- 558Tendonitis, Myositis and Bursitis without MCCmedical
As a secondary diagnosis, M79.A19 is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG.
How is M79.A19 listed in the Alphabetic Index?
The Alphabetic Index lists these routes under M79.A1, the nearest indexed parent of M79.A19. Use them to find the family, then select the specific code.
- Compartment syndrome › nontraumatic › upper extremity (deep) (posterior) (traumatic)
- Syndrome › compartment › nontraumatic › upper extremity
Excludes1 — never code together — inherited from M79
The conditions below can never be reported together with M79.A19 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Excludes1 — never code together — inherited from M79.A
The conditions below can never be reported together with M79.A19 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Code first — inherited from M79.A
The underlying condition below must be sequenced before M79.A19. M79.A19 describes a manifestation and cannot be the principal or first-listed diagnosis.
- , if applicable, associated postprocedural complication
Excludes2 — not included here — inherited from Chapter 13
The conditions below are not part of M79.A19, but a patient may have both at the same time. When documentation supports it, M79.A19 and the excluded code may both be reported.
- arthropathic psoriasis (L40.5-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- compartment syndrome (traumatic) (T79.A-)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
How long has M79.A19 existed?
M79.A19 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.