Skip to main content

A03.9 ICD-10-CM Code: Shigellosis, unspecified

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

Coding at a Glance

Tabular directives
1 inclusion term

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 v44, Appendix B.

  • MS-DRG 371 — MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITH MCC (MDC 06)
  • MS-DRG 372 — MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITH CC (MDC 06)
  • MS-DRG 373 — MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITHOUT CC/MCC (MDC 06)

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.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for A03.9 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Bacillary dysentery NOS

Coder workflow for A03.9

MedCoder structured workflow — derived from this code’s own official record

Before you code A03.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, A03.9 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewA03.0, A03.1, A03.2, A03.3, A03.8

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — A03.9 is appropriate when the documentation goes no further.

    ReviewA03.0, A03.1, A03.2, A03.3, A03.8

Consider A03.9. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewA03.0, A03.1, A03.2, A03.3, A03.8

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Shigellosis, unspecified is a billable ICD-10-CM diagnosis code (A03.9).

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 (10)

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

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

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 A03.9 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 6 Excludes2 notes: P35 — Congenital viral diseases (via A03.-), P35-P39 — Infections specific to the perinatal period (P35-P39) (via A03.-), P36 — Bacterial sepsis of newborn (via A03.-), P37 — Other congenital infectious and parasitic diseases (via A03.-), P38 — Omphalitis of newborn (via A03.-), P39 — Other infections specific to the perinatal period (via A03.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 1 Code First instruction: M49 — Spondylopathies in diseases classified elsewhere (via A03.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

Referenced by 1 Use Additional Code instruction: D59.31 — Infection-associated hemolytic-uremic syndrome.

These codes instruct coders to additionally report this code when it applies.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

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).

A01.3 — Paratyphoid fever C, A01.4 — Paratyphoid fever, unspecified, A02.0 — Salmonella enteritis, A02.29 — Salmonella with other localized infection, A02.9 — Salmonella infection, unspecified, A03.0 — Shigellosis due to Shigella dysenteriae, A03.1 — Shigellosis due to Shigella flexneri, A03.2 — Shigellosis due to Shigella boydii, A03.3 — Shigellosis due to Shigella sonnei, A03.8 — Other shigellosis, A04.0 — Enteropathogenic Escherichia coli infection, A04.1 — Enterotoxigenic Escherichia coli infection, A04.2 — Enteroinvasive Escherichia coli infection, A04.3 — Enterohemorrhagic Escherichia coli infection, A04.4 — Other intestinal Escherichia coli infections, A04.5 — Campylobacter enteritis, A04.6 — Enteritis due to Yersinia enterocolitica, A04.7 — Enterocolitis due to Clostridium difficile, A04.71 — Enterocolitis due to Clostridium difficile, recurrent, A04.72 — Enterocolitis due to Clostridium difficile, not specified as recurrent, +404 more

Same Index main term, other category

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

A00.1 — Cholera due to Vibrio cholerae 01, biovar eltor (eltor), A01.00 — Typhoid fever, unspecified (typhosa), A02.0 — Salmonella enteritis (aertrycke infection), A02.1 — Salmonella sepsis (Salmonella), A04.0 — Enteropathogenic Escherichia coli infection (infectious NOS, due to, Escherichia coli, enteropathogenic), A04.1 — Enterotoxigenic Escherichia coli infection (infectious NOS, due to, Escherichia coli, enterotoxigenic), A04.2 — Enteroinvasive Escherichia coli infection (infectious NOS, due to, Escherichia coli, enteroinvasive), A04.3 — Enterohemorrhagic Escherichia coli infection (infectious NOS, due to, Escherichia coli, enterohemorrhagic), A04.4 — Other intestinal Escherichia coli infections (infectious NOS, due to, Escherichia coli), A04.5 — Campylobacter enteritis (infectious NOS, due to, Campylobacter), A04.6 — Enteritis due to Yersinia enterocolitica (due to, Yersinia enterocolitica), A04.71 — Enterocolitis due to Clostridium difficile, recurrent (Clostridium, difficile, recurrent), A04.72 — Enterocolitis due to Clostridium difficile, not specified as recurrent (Clostridium, difficile, not specified as recurrent), A04.8 — Other specified bacterial intestinal infections (staphylococcal), A04.9 — Bacterial intestinal infection, unspecified (bacterial), A05.0 — Foodborne staphylococcal intoxication (staphylococcal, due to food), A05.1 — Botulism food poisoning (Clostridium, botulinum), A05.2 — Foodborne Clostridium perfringens [Clostridium welchii] intoxication (necroticans), A06.0 — Acute amebic dysentery (amebic), A06.1 — Chronic intestinal amebiasis (amebic, chronic), +139 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.

Fecal Occult Blood Test (FOBT)

Contextual Map

Every relationship of A03.9 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 A03.9 with these 8 related codes in Claim Check

Hierarchy

Referenced by Excludes2 notes

Referenced by Code First instructions

Referenced by Use Additional Code instructions

Clinical classification (CCSR)

MS-DRG Grouper

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. 5,748 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries (10)

  • Chinese dysentery[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Dysentery, dysenteric (catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical), arthritis, bacillary[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Dysentery, dysenteric (catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical), bacillary[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Dysentery, dysenteric (catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical), bacillary, arthritis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Dysentery, dysenteric (catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical), bacillary, Shigella[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Dysentery, dysenteric (catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical), Chinese[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Enteritis (acute) (diarrheal) (hemorrhagic) (noninfective), bacillary NOS[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Infection, infected, infective (opportunistic), Shigella[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • and 2 more

Nearest codes

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 FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 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 — v44 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. "A03.9 — Shigellosis, unspecified." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/a03.9-shigellosis-unspecified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Shigellosis, unspecified

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

Nearest Codes in This Family

Official ICD-10-CM classifications closest to A03.9 in its code family, with their registry titles.

View all codes in the A03 family