Skip to content
Dx

ICD-10-CM 2027 diagnosis code

A91Dengue hemorrhagic fever

✓ Billable / specificCC — complication/comorbidity

A91 is a valid, billable ICD-10-CM code for dengue hemorrhagic fever. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Looking up by condition? See ICD-10 code for Bangkok hemorrhagic fever, ICD-10 code for Southeast Asian hemorrhagic fever.

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 A91

A91 is the ICD-10-CM diagnosis code for dengue hemorrhagic fever. It belongs to block A90-A99 (arthropod-borne viral fevers and viral hemorrhagic fevers) 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.

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" 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 865 (Viral Illness with MCC, relative weight 1.3485) and DRG 866 (Viral Illness without MCC, relative weight 0.8692), in MDC 18 (Infectious and Parasitic Diseases, Systemic or Unspecified Sites), 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 065.4 (mosquito-borne hemorrhagic fever).

Notes that apply from higher levels

Instructions written at a parent level also apply to A91.

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

Alphabetic index entries

17 entries

Terms in the official ICD-10-CM index that lead to A91.

Codes whose notes reference A91

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.

MDC 18 · Infectious and Parasitic Diseases, Systemic or Unspecified Sites

ICD-9-CM equivalent

Converter →
  • 065.4Mosquito-borne hemorrhagic feverapproximate

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 A91

Is A91 billable?

Yes. A91 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can A91 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict A91 as a principal diagnosis.

Is A91 a CC or MCC?

A91 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does A91 group to?

A91 is used in the MS-DRG v44.0 logic for MS-DRG 865 (Viral Illness with MCC) and MS-DRG 866 (Viral Illness without 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 A91?

The CMS General Equivalence Mappings map A91 to ICD-9-CM 065.4.