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A56.3 ICD-10-CM Code: Chlamydial infection of anus and rectum

Compare with another code for A56.3Check 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 inclusion terms · 4 Excludes1 · 3 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.

Excludes1Not reported with this code unless documented as unrelated
  • neonatal chlamydial conjunctivitis (P39.1) (from A56)
  • neonatal chlamydial pneumonia (P23.1) (from A56)
  • nonspecific and nongonococcal urethritis (N34.1) (from A50-A64)
  • Reiter's disease (M02.3-) (from A50-A64)
Excludes2Not included here; may be reported together
  • chlamydial lymphogranuloma (A55) (from A56)
  • conditions classified to A74.- (from A56)
  • human immunodeficiency virus [HIV] disease (B20) (from A50-A64)
Includesfrom A56What A56 covers
  • sexually transmitted diseases due to Chlamydia
  • trachomatis

Where it sits Source: CMS/NCHS

Under:Chapter 1: Certain Infectious and Parasitic DiseasesA50-A64 Infections with a predominantly sexual mode of transmissionA56 Other sexually transmitted chlamydial diseases

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 393 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITH MCC (MDC 06)
  • MS-DRG 394 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITH CC (MDC 06)
  • MS-DRG 395 — OTHER DIGESTIVE SYSTEM DIAGNOSES 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 A56.3 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 A56.3 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • sexually transmitted diseases due to Chlamydia
  • trachomatis

Source: inherited from A56

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Excludes2 — Not Included Here

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

Coder workflow for A56.3

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

Before you code A56.3

  1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with A56.3. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support a condition named in A56.3’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewP39.1, P23.1, N34.1, M02.3

Consider A56.3. 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).

Official instructions as workflow

  • Excludes1 — check before selecting A56.3(4 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with A56.3: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareP39.1, P23.1, N34.1, M02.3

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

  • Excludes2 — not part of A56.3(3 notes)

    Coding workflow: The conditions named in this note are not included in A56.3. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareA55, A74, B20

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

Coding decision scenarios

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

Documentation: Both the condition A56.3 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewP39.1, P23.1, N34.1, M02.3

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 A56.3 with…

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

The codes most likely to be picked instead of A56.3 — 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.

  • P39.1— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of neonatal chlamydial conjunctivitis moves the case to P39.1; the two are not reported together unless documented as unrelated.

    Full comparison: A56.3 vs P39.1 →

  • P23.1— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of neonatal chlamydial pneumonia moves the case to P23.1; the two are not reported together unless documented as unrelated.

    Full comparison: A56.3 vs P23.1 →

  • N34.1— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of nonspecific and nongonococcal urethritis moves the case to N34.1; the two are not reported together unless documented as unrelated.

    Full comparison: A56.3 vs N34.1 →

  • M02.3— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of Reiter's disease moves the case to M02.3; the two are not reported together unless documented as unrelated.

    Full comparison: A56.3 vs M02.3 →

  • A56.2— 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 “Chlamydial infection of genitourinary tract, unspecified” takes A56.2; specificity in the record moves it back here.

    Full comparison: A56.3 vs A56.2 →

  • A55— 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 chlamydial lymphogranuloma adds A55; it is not part of this code and both may be reported when both are documented.

    Full comparison: A56.3 vs A55 →

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

Chlamydial infection of anus and rectum is a billable ICD-10-CM diagnosis code (A56.3).

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

  • 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-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name A56.3 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 4 Excludes1 notes: A70 — Chlamydia psittaci infections (via A56.-), A70-A74 — Other diseases caused by chlamydiae (A70-A74) (via A56.-), A71 — Trachoma (via A56.-), A74 — Other diseases caused by chlamydiae (via A56.-).

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

Referenced by 1 Excludes2 note: N34 — Urethritis and urethral syndrome (via A56.-).

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

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 393 (MDC 06), DRG 394 (MDC 06), DRG 395 (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):INF010 — Sexually transmitted infections (excluding HIV and hepatitis) (default); DIG015 — Anal and rectal conditions.

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 (Sexually transmitted infections (excluding HIV and hepatitis), Anal and rectal conditions).

A54.89 — Other gonococcal infections, A54.9 — Gonococcal infection, unspecified, A55 — Chlamydial lymphogranuloma (venereum), A56.00 — Chlamydial infection of lower genitourinary tract, unspecified, A56.01 — Chlamydial cystitis and urethritis, A56.02 — Chlamydial vulvovaginitis, A56.09 — Other chlamydial infection of lower genitourinary tract, A56.11 — Chlamydial female pelvic inflammatory disease, A56.19 — Other chlamydial genitourinary infection, A56.2 — Chlamydial infection of genitourinary tract, unspecified, A56.4 — Chlamydial infection of pharynx, A56.8 — Sexually transmitted chlamydial infection of other sites, A57 — Chancroid, A58 — Granuloma inguinale, A59.00 — Urogenital trichomoniasis, unspecified, A59.01 — Trichomonal vulvovaginitis, A59.02 — Trichomonal prostatitis, A59.03 — Trichomonal cystitis and urethritis, A59.09 — Other urogenital trichomoniasis, A59.8 — Trichomoniasis of other sites, +192 more

Same Index main term, other category

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

A06.0 — Acute amebic dysentery (amebic), A18.32 — Tuberculous enteritis (tuberculous), A54.6 — Gonococcal infection of anus and rectum (gonococcal), A60.1 — Herpesviral infection of perianal skin and rectum (herpetic), A70 — Chlamydia psittaci infections (psittaci), A74.0 — Chlamydial conjunctivitis (conjunctivitis), A74.81 — Chlamydial peritonitis (peritonitis), A74.89 — Other chlamydial diseases (specified NEC), A74.9 — Chlamydial infection, unspecified, K51.20 — Ulcerative (chronic) proctitis without complications (ulcerative), K51.211 — Ulcerative (chronic) proctitis with rectal bleeding (ulcerative, with, complication, rectal bleeding), K51.212 — Ulcerative (chronic) proctitis with intestinal obstruction (ulcerative, with, complication, obstruction), K51.213 — Ulcerative (chronic) proctitis with fistula (ulcerative, with, complication, fistula), K51.214 — Ulcerative (chronic) proctitis with abscess (ulcerative, with, complication, abscess), K51.218 — Ulcerative (chronic) proctitis with other complication (ulcerative, with, complication, specified NEC), K51.219 — Ulcerative (chronic) proctitis with unspecified complications (ulcerative, with, complication), K62.7 — Radiation proctitis (radiation), K62.89 — Other specified diseases of anus and rectum

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 A56.3 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 A56.3 with these 5 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes

  • N34 — Urethritis and urethral syndrome[Excludes2](via A56.-): “urethritis in diseases with a predominantly sexual mode of transmission (A50-A64)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2027

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

  • Chlamydia, chlamydial, proctitis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, venereal, chlamydial NEC, anus[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, venereal, chlamydial NEC, rectum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Infection, infected, infective (opportunistic), Chlamydia, chlamydial, anus[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Infection, infected, infective (opportunistic), Chlamydia, chlamydial, rectum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Proctitis, chlamydial[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027

Nearest codes (12)

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 (6)

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. "A56.3 — Chlamydial infection of anus and rectum." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/a56.3-chlamydial-infection-of-anus-and-rectum

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Chlamydial infection of anus and rectum

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 A56.3 in its code family, with their registry titles.

View all codes in the A56 family