ICD-10 A37.91
Billable / Specific MCCWhooping cough, unspecified species with pneumonia
About ICD-10-CM A37.91
ICD-10-CM code A37.91 represents Whooping cough, unspecified species with pneumonia. This is a billable/specific code in the Infectious and Parasitic Diseases chapter (block A37). The 2026 edition of ICD-10-CM A37.91 became effective on October 1, 2025.
Coding Tips for A37.91
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
A37.91 is designated MCC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-MCC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag MCC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inpatient DRG Impact, MCC
codes Whooping cough, unspecified species with pneumonia. As a Major Complication/Comorbidity (MCC), this can shift the DRG assignment to a higher-weighted category, substantial reimbursement impact.
Medicare LCD Coverage for A37.91
Local Coverage Determinations (LCDs) from CMS MACs that list A37.91 as a covered diagnosis.
Showing top 10 of 584 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing A37.91.
2 Aetna
5 Medicare
CPT Codes Commonly Billed with A37.91
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 94726 CMS LCD: Billing and Coding: Respiratory Therapy (Respiratory Care) CMS LCD
- 94004 CMS LCD: Billing and Coding: Respiratory Therapy (Respiratory Care) CMS LCD
- 94621 CMS LCD: Billing and Coding: Respiratory Therapy (Respiratory Care) CMS LCD
- 94011 CMS LCD: Billing and Coding: Respiratory Therapy (Respiratory Care) CMS LCD
- 94003 CMS LCD: Billing and Coding: Respiratory Therapy (Respiratory Care) CMS LCD
- 94668 CMS LCD: Billing and Coding: Respiratory Therapy (Respiratory Care) CMS LCD
- 94070 CMS LCD: Billing and Coding: Respiratory Therapy (Respiratory Care) CMS LCD
- 94664 CMS LCD: Billing and Coding: Respiratory Therapy (Respiratory Care) CMS LCD
- 94012 CMS LCD: Billing and Coding: Respiratory Therapy (Respiratory Care) CMS LCD
- 31502 CMS LCD: Billing and Coding: Respiratory Therapy (Respiratory Care) CMS LCD
Convert A37.91 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| A37.91 | 0339 | 10111 |
| A37.91 | 4843 | 10112 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To A37.91
Other codes in section A30-A49 (Other bacterial diseases).
ICD-10 A37.91, Billing FAQ
Is ICD-10 code A37.91 billable? +
Yes, A37.91 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Is A37.91 a CC or MCC for inpatient DRG? +
Yes, this code is designated as MCC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with A37.91? +
Procedures frequently paired with A37.91 include: 94726, 94004, 94621, 94011, 94003.
What ICD-9 codes does A37.91 map to? +
Per CMS GEMs, A37.91 maps to ICD-9 codes: 0339, 4843. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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