A22.2 ICD-10-CM Code: Gastrointestinal anthrax

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for A22.2 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on A22.2 itself; “inherited from” names the category or block whose note applies here.

Indexed Clinical Terms (4)

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.

• Anthrax, colitis
• Anthrax, gastrointestinal
• Anthrax, intestinal
• Colitis (acute) (catarrhal) (chronic) (noninfective) (hemorrhagic), anthrax

Don’t confuse A22.2 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of A22.2 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• A22.9— Specificity relationship (Review)

  Overlapping diagnoses in the same category.

  Overlapping codes in the same category — the documentation decides which is the more specific fit.

  What moves you there: A record that documents no more than “Anthrax, unspecified” takes A22.9; specificity in the record moves it back here.

  Full comparison: A22.2 vs A22.9 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

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

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 1 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 3 MS-DRGs: DRG 371 (MDC 06), DRG 372 (MDC 06), DRG 373 (MDC 06).

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

Clinical classification (AHRQ CCSR):DIG001 — Intestinal infection (default); INF003 — Bacterial infections.

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 category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Intestinal infection, Bacterial infections).

A07.0 — Balantidiasis, A07.1 — Giardiasis [lambliasis], A07.2 — Cryptosporidiosis, A07.3 — Isosporiasis, A07.4 — Cyclosporiasis, A07.8 — Other specified protozoal intestinal diseases, A07.9 — Protozoal intestinal disease, unspecified, A08.0 — Rotaviral enteritis, A08.11 — Acute gastroenteropathy due to Norwalk agent, A08.19 — Acute gastroenteropathy due to other small round viruses, A08.2 — Adenoviral enteritis, A08.31 — Calicivirus enteritis, A08.32 — Astrovirus enteritis, A08.39 — Other viral enteritis, A08.4 — Viral intestinal infection, unspecified, A08.8 — Other specified intestinal infections, A09 — Infectious gastroenteritis and colitis, unspecified, A18.32 — Tuberculous enteritis, A21.3 — Gastrointestinal tularemia, B37.82 — Candidal enteritis, +404 more

Same Index main term, other category

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

A05.0 — Foodborne staphylococcal intoxication (staphylococcal, foodborne), A06.0 — Acute amebic dysentery (amebic), A06.2 — Amebic nondysenteric colitis (amebic, nondysenteric), A07.0 — Balantidiasis (balantidial), A07.1 — Giardiasis [lambliasis] (giardial), A07.3 — Isosporiasis (coccidial), A07.8 — Other specified protozoal intestinal diseases (trichomonal), A07.9 — Protozoal intestinal disease, unspecified (protozoal), A09 — Infectious gastroenteritis and colitis, unspecified (regional, infectious), A18.32 — Tuberculous enteritis (tuberculous), F54 — Psychological and behavioral factors associated with disorders or diseases classified elsewhere (mucous, psychogenic), K51.50 — Left sided colitis without complications (left sided), K51.511 — Left sided colitis with rectal bleeding (left sided, with, rectal bleeding), K51.512 — Left sided colitis with intestinal obstruction (left sided, with, obstruction), K51.513 — Left sided colitis with fistula (left sided, with, fistula), K51.514 — Left sided colitis with abscess (left sided, with, abscess), K51.518 — Left sided colitis with other complication (left sided, with, complication, specified NEC), K51.519 — Left sided colitis with unspecified complications (left sided, with, complication), K51.80 — Other ulcerative colitis without complications (ulcerative, specified type NEC), K51.811 — Other ulcerative colitis with rectal bleeding (ulcerative, specified type NEC, with, complication, rectal bleeding), +33 more

Contextual Map

Every relationship of A22.2 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.

Hierarchy

• A00-B99 — Chapter 1: Certain Infectious and Parasitic Diseases (A00-B99) (A00-B99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A20-A28 — Certain zoonotic bacterial diseases[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Clinical classification (CCSR)

• DIG001 — Intestinal infection[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)
• INF003 — Bacterial infections[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

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 371 — MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITH MCC[MS-DRG]: “MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITH MCC (MDC 06)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 372 — MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITH CC[MS-DRG]: “MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITH CC (MDC 06)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 373 — MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITHOUT CC/MCC[MS-DRG]: “MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITHOUT CC/MCC (MDC 06)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 06 — Diseases and Disorders of the Digestive System[MDC crossing]: “Diseases and Disorders of the Digestive System — 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. 5,744 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Anthrax, colitis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Anthrax, gastrointestinal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Anthrax, intestinal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Colitis (acute) (catarrhal) (chronic) (noninfective) (hemorrhagic), anthrax[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

• A22 — Anthrax[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A22.0 — Cutaneous anthrax[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A22.1 — Pulmonary anthrax[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A22.7 — Anthrax sepsis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A22.8 — Other forms of anthrax[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• A22.9 — Anthrax, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

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

Nearest Codes in This Family

Official ICD-10-CM classifications closest to A22.2 in its code family, with their registry titles.

• A22 — Anthrax
• A22.0 — Cutaneous anthrax
• A22.1 — Pulmonary anthrax
• A22.7 — Anthrax sepsis
• A22.8 — Other forms of anthrax
• A22.9 — Anthrax, unspecified

View all codes in the A22 family