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ICD-10-CM 2027 diagnosis code

A37.11Whooping cough due to Bordetella parapertussis with pneumonia

✓ Billable / specificMCC — major complication/comorbidity

A37.11 is a valid, billable ICD-10-CM code for whooping cough due to bordetella parapertussis with pneumonia. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Whooping cough due to Bordetella parapertussis w pneumonia

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About A37.11

A37.11 is the ICD-10-CM diagnosis code for whooping cough due to Bordetella parapertussis with pneumonia. It belongs to category A37 (whooping cough), block A30-A49 (other bacterial diseases) and chapter 1 (certain infectious and parasitic diseases). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within A37.1 (whooping cough due to Bordetella parapertussis), A37.11 is specifically for whooping cough due to Bordetella parapertussis with pneumonia. Related codes cover without pneumonia (A37.10).

As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 202 (Bronchitis and Asthma with CC/MCC, relative weight 0.9474) and DRG 203 (Bronchitis and Asthma without CC/MCC, relative weight 0.6512), in MDC 04 (Diseases and Disorders of the Respiratory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 033.1 (whooping cough due to bordetella parapertussis [B. parapertussis]) and 484.3 (pneumonia in whooping cough).

Notes that apply from higher levels

Instructions written at a parent level also apply to A37.11.

Broader instructions also apply from Chapter 1: Certain infectious and parasitic diseases.

Alphabetic index entries

3 entries

Terms in the official ICD-10-CM index that lead to A37.11.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 033.1Whooping cough due to bordetella parapertussis [B. parapertussis]approximate, combination
  • 484.3Pneumonia in whooping coughapproximate, combination

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about A37.11

Is A37.11 billable?

Yes. A37.11 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can A37.11 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict A37.11 as a principal diagnosis.

Is A37.11 a CC or MCC?

A37.11 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does A37.11 group to?

A37.11 is used in the MS-DRG v44.0 logic for MS-DRG 202 (Bronchitis and Asthma with CC/MCC) and MS-DRG 203 (Bronchitis and Asthma without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for A37.11?

The CMS General Equivalence Mappings map A37.11 to ICD-9-CM 033.1 and 484.3.