A37.91 — Whooping cough, unspecified species with pneumonia
Is A37.91 billable?
Yes, but A37.91 is an unspecified code. A37.91 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, A37.91 is an unspecified or catch-all code. Payers apply additional scrutiny to unspecified codes and many deny them when the medical record supports a more specific option, so check the documentation before selecting A37.91 — the more specific alternatives are listed below.
More specific alternatives
A37.91 at a glance
| Code | A37.91 |
|---|---|
| Description | Whooping cough, unspecified species with pneumonia |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does A37.91 group to?
A37.91 sits in MDC 04 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.
- 202Bronchitis and Asthma with CC/MCCmedical
- 203Bronchitis and Asthma without CC/MCCmedical
As a secondary diagnosis, A37.91 is a major complication or comorbidity (MCC), which can move a stay into a higher-paying DRG.
How is A37.91 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to A37.91. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Whooping cough › with pneumonia
- Pneumonia › in › whooping cough (acute) (double) (migratory) (purulent) (septic) (unresolved)
Use additional code — inherited from Chapter 1
Report an additional code alongside A37.91 to fully describe the condition. A37.91 is sequenced first.
- code to identify resistance to antimicrobial drugs (Z16.-)
Excludes2 — not included here — inherited from Chapter 1
The conditions below are not part of A37.91, but a patient may have both at the same time. When documentation supports it, A37.91 and the excluded code may both be reported.
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
How long has A37.91 existed?
A37.91 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.