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A91 ICD-10-CM Code: Dengue hemorrhagic fever

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Code Overview

Dengue hemorrhagic fever is a billable ICD-10-CM diagnosis code (A91).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (17)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Verify Before Coding

  • CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name A91 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 2 Excludes1 notes: A90 — Dengue fever [classical dengue], A98 — Other viral hemorrhagic fevers, not elsewhere classified.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 23 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 865 (MDC 18), DRG 866 (MDC 18).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):INF008 — Viral infection (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

A92.0 — Chikungunya virus disease, A92.1 — O'nyong-nyong fever, A92.2 — Venezuelan equine fever, A92.30 — West Nile virus infection, unspecified, A92.31 — West Nile virus infection with encephalitis, A92.32 — West Nile virus infection with other neurologic manifestation, A92.39 — West Nile virus infection with other complications, A92.4 — Rift Valley fever, A92.5 — Zika virus disease, A92.8 — Other specified mosquito-borne viral fevers, A92.9 — Mosquito-borne viral fever, unspecified, A93.0 — Oropouche virus disease, A93.1 — Sandfly fever, A93.2 — Colorado tick fever, A93.8 — Other specified arthropod-borne viral fevers, A94 — Unspecified arthropod-borne viral fever, A98.0 — Crimean-Congo hemorrhagic fever, A98.1 — Omsk hemorrhagic fever, A98.2 — Kyasanur Forest disease, A98.8 — Other specified viral hemorrhagic fevers, +2 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Viral infection).

+309 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Fever”, “Dengue”; these codes share that main term but sit in a different category of the Tabular List.

A77.41 — Ehrlichiosis chaffeensis [E. chaffeensis] (spotted, Ehrlichiosis, due to, E. chaffeensis), A77.49 — Other ehrlichiosis (spotted, Ehrlichiosis, due to, specified organism NEC), A77.8 — Other spotted fevers (African tick bite), A77.9 — Spotted fever, unspecified (spotted), A78 — Q fever (Q), A79.0 — Trench fever (Meuse), A79.1 — Rickettsialpox due to Rickettsia akari (Kew Garden), A80.4 — Acute nonparalytic poliomyelitis (polioviral), A88.0 — Enteroviral exanthematous fever [Boston exanthem] (enteroviral exanthematous), A90 — Dengue fever [classical dengue], A92.0 — Chikungunya virus disease (Chikungunya), A92.1 — O'nyong-nyong fever (O'nyong-nyong), A92.2 — Venezuelan equine fever (Venezuelan equine), A92.30 — West Nile virus infection, unspecified (West, Nile), A92.31 — West Nile virus infection with encephalitis (West, Nile, with, encephalitis), A92.32 — West Nile virus infection with other neurologic manifestation (West, Nile, with, optic neuritis), A92.39 — West Nile virus infection with other complications (West, Nile, with, complications NEC), A92.4 — Rift Valley fever (Rift Valley), A92.5 — Zika virus disease (Zika virus), A92.8 — Other specified mosquito-borne viral fevers (Guama), +109 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Partial Thromboplastin Time (PTT) Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of A91 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run A91 with these 2 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Clinical classification (CCSR)

MS-DRG Grouper

  • CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
  • DRG 865 — VIRAL ILLNESS WITH MCC[MS-DRG]: “VIRAL ILLNESS WITH MCC (MDC 18)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
  • DRG 866 — VIRAL ILLNESS WITHOUT MCC[MS-DRG]: “VIRAL ILLNESS WITHOUT MCC (MDC 18)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

  • MDC 18 — Infectious and Parasitic Diseases, Systemic or Unspecified Sites[MDC crossing]: “Infectious and Parasitic Diseases, Systemic or Unspecified Sites — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 1 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries (17)

  • Bangkok hemorrhagic fever[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Dengue (classical) (fever), hemorrhagic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), Bangkok hemorrhagic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), dengue (virus), hemorrhagic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), hemorrhagic NOS (arthropod-borne), Bangkok[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), hemorrhagic NOS (arthropod-borne), dengue (virus)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), hemorrhagic NOS (arthropod-borne), Philippine[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), hemorrhagic NOS (arthropod-borne), Singapore[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • and 9 more

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "A91 — Dengue hemorrhagic fever." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/a91-dengue-hemorrhagic-fever

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Dengue hemorrhagic fever

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.