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A31.8 ICD-10-CM Code: Other mycobacterial infections

Compare with another code for A31.8Check this code on a claim

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

Coding at a Glance

Tabular directives
2 Excludes2

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

Excludes2from A31Not included here; may be reported together

Where it sits Source: CMS/NCHS

Under:Chapter 1: Certain Infectious and Parasitic DiseasesA30-A49 Other bacterial diseasesA31 Infection due to other mycobacteria

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

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 867 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH MCC (MDC 18)
  • MS-DRG 868 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH CC (MDC 18)
  • MS-DRG 869 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITHOUT CC/MCC (MDC 18)
  • MS-DRG 974 — HIV WITH MAJOR RELATED CONDITION WITH MCC (MDC 25)
  • MS-DRG 975 — HIV WITH MAJOR RELATED CONDITION WITH CC (MDC 25)
  • MS-DRG 976 — HIV WITH MAJOR RELATED CONDITION WITHOUT CC/MCC (MDC 25)

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 A31.8 in the official ICD-10-CM tabular list, quoted as published.

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

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on A31.8 itself; “inherited from” names the category or block whose note applies here.

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from A31

Coder workflow for A31.8

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

Before you code A31.8

  1. “Other” (NEC) means the condition is specified in the record but no dedicated code captures it. Confirm the documented form is not one a sibling code names before settling on A31.8; if the record states no specifics at all, the unspecified sibling applies instead. “Other” codes are for documented conditions the classification gives no specific code; “unspecified” codes are for records lacking the detail (Guidelines I.A.9.a, I.A.9.b).

    ReviewA31.0, A31.1, A31.2

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

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 code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes2 — not part of A31.8(2 notes)

    Coding workflow: The conditions named in this note are not included in A31.8. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareA30

    See the official tabular notes · Guidelines I.A.12.b

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.

Don’t confuse A31.8 with…

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

The codes most likely to be picked instead of A31.8 — 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.

  • A31.9— 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 “Mycobacterial infection, unspecified” takes A31.9; specificity in the record moves it back here.

    Full comparison: A31.8 vs A31.9 →

  • A30— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of leprosy adds A30; it is not part of this code and both may be reported when both are documented.

    Full comparison: A31.8 vs A30 →

  • A15— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of tuberculosis adds A15; it is not part of this code and both may be reported when both are documented.

    Full comparison: A31.8 vs A15 →

  • A19— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of tuberculosis adds A19; it is not part of this code and both may be reported when both are documented.

    Full comparison: A31.8 vs A19 →

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.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Other mycobacterial infections is a billable ICD-10-CM diagnosis code (A31.8).

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

Verify Before Coding

  • CC as a secondary diagnosis (FY2027). 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-derived relationships — computed from published CMS and AHRQ datasets

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 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 5 clinically related codes on its CMS exclusion list. Does not count toward severity when the stay groups to DRGs 974-976 (HIV with Major Related Condition).

Named in the grouper logic of 6 MS-DRGs: DRG 867 (MDC 18), DRG 868 (MDC 18), DRG 869 (MDC 18), DRG 974 (MDC 25), DRG 975 (MDC 25), DRG 976 (MDC 25).

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

Clinical classification (AHRQ CCSR):INF003 — Bacterial infections (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.

A31.0 — Pulmonary mycobacterial infection, A31.1 — Cutaneous mycobacterial infection, A31.2 — Disseminated mycobacterium avium-intracellulare complex (DMAC), A31.9 — Mycobacterial infection, unspecified

Same clinical category (CCSR)

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

+399 more

Same Index main term, other category

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

A01.4 — Paratyphoid fever, unspecified (in, paratyphoid fever), A02.23 — Salmonella arthritis (in, Salmonella), A08.8 — Other specified intestinal infections (in, enteritis, infectious NEC, specified organism NEC), A09 — Infectious gastroenteritis and colitis, unspecified (in, enteritis, infectious NEC), A18.01 — Tuberculosis of spine (spine, tuberculous), A18.02 — Tuberculous arthritis of other joints (tuberculous), A18.39 — Retroperitoneal tuberculosis (mesenteric, tuberculous), A24.0 — Glanders (due to or associated with, glanders), A25.1 — Streptobacillosis (epidemic erythema), A30.9 — Leprosy, unspecified (in, leprosy), A36.89 — Other diphtheritic complications (due to, diphtheria), A39.83 — Meningococcal arthritis (meningococcal), A39.84 — Postmeningococcal arthritis (postmeningococcal), A46 — Erysipelas (due to or associated with, erysipelas), A49.9 — Bacterial infection, unspecified (in, bacterial disease), A50.55 — Late congenital syphilitic arthropathy (syphilitic, congenital), A51.49 — Other secondary syphilitic conditions (syphilitic), A52.16 — Charcôt's arthropathy (tabetic) (syphilitic), A52.79 — Other symptomatic late syphilis (syphilitic, late), A54.42 — Gonococcal arthritis (gonococcal), +218 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.

HIV Screening Test

Contextual Map

Every relationship of A31.8 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

Clinical classification (CCSR)

MS-DRG Grouper

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 · FY2027
  • MDC 25 — Human Immunodeficiency Virus Infections[MDC crossing]: “Human Immunodeficiency Virus Infections — 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.”— CMS MS-DRG Definitions Manual · FY2027

Index entries (15)

  • Arthritis, arthritic (acute) (chronic) (nonpyogenic) (subacute), due to or associated with, mycobacteria[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Lymphadenitis, mycobacterial[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Mycobacterium, mycobacterial (infection), atypical, specified site NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Mycobacterium, mycobacterial (infection), chelonei[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Mycobacterium, mycobacterial (infection), extrapulmonary systemic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Mycobacterium, mycobacterial (infection), fortuitum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Mycobacterium, mycobacterial (infection), kakaferifu[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Mycobacterium, mycobacterial (infection), kasongo[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • and 7 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

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Indexed Clinical Terms (15)

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.

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-derived 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 editorial 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.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

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. "A31.8 — Other mycobacterial infections." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/a31.8-other-mycobacterial-infections

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Other mycobacterial infections

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 A31.8 in its code family, with their registry titles.

View all codes in the A31 family