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N45.1 ICD-10-CM Code: Epididymitis

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

Coding at a Glance

Tabular directives
1 use-additional code

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.

  • MS-DRG 727 — INFLAMMATION OF THE MALE REPRODUCTIVE SYSTEM WITH MCC (MDC 12)
  • MS-DRG 728 — INFLAMMATION OF THE MALE REPRODUCTIVE SYSTEM WITHOUT MCC (MDC 12)

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 N45.1 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 N45.1 itself; “inherited from” names the category or block whose note applies here.

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code (B95-B97), to identify infectious agent.

Source: inherited from N45

Coder workflow for N45.1

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

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).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

  • Use Additional Code — after identifying N45.1(1 note)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with N45.1 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

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

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with N45.1?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

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

Epididymitis is a billable ICD-10-CM diagnosis code (N45.1).

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 (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.

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 N45.1 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 1 Excludes1 note: N49 — Inflammatory disorders of male genital organs, not elsewhere classified (via N45.-).

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: 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 2 MS-DRGs: DRG 727 (MDC 12), DRG 728 (MDC 12).

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

Clinical classification (AHRQ CCSR):GEN013 — Inflammatory conditions of male genital organs (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 category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Inflammatory conditions of male genital organs).

B37.42 — Candidal balanitis, B38.81 — Prostatic coccidioidomycosis, N41.0 — Acute prostatitis, N41.1 — Chronic prostatitis, N41.2 — Abscess of prostate, N41.3 — Prostatocystitis, N41.4 — Granulomatous prostatitis, N41.8 — Other inflammatory diseases of prostate, N41.9 — Inflammatory disease of prostate, unspecified, N43.1 — Infected hydrocele, N45.2 — Orchitis, N45.3 — Epididymo-orchitis, N45.4 — Abscess of epididymis or testis, N47.6 — Balanoposthitis, N48.1 — Balanitis, N48.21 — Abscess of corpus cavernosum and penis, N48.22 — Cellulitis of corpus cavernosum and penis, N48.29 — Other inflammatory disorders of penis, N49.0 — Inflammatory disorders of seminal vesicle, N49.1 — Inflammatory disorders of spermatic cord, tunica vaginalis and vas deferens, +12 more

Same Index main term, other category

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

I96 — Gangrene, not elsewhere classified, J04.0 — Acute laryngitis (laryngitis), J36 — Peritonsillar abscess (quinsy), J39.2 — Other diseases of pharynx (retropharyngeal), J85.0 — Gangrene and necrosis of lung (lung), K04.1 — Necrosis of pulp (tooth), K12.2 — Cellulitis and abscess of mouth (uvulitis), K14.0 — Glossitis (glossitis), K35.31 — Acute appendicitis with localized peritonitis and gangrene, without perforation (appendix, with, peritonitis, localized), K35.80 — Unspecified acute appendicitis (appendix), K55.069 — Acute infarction of intestine, part and extent unspecified (mesentery), M27.3 — Alveolitis of jaws (alveolar), N44.8 — Other noninflammatory disorders of the testis (testis, noninfective), N48.29 — Other inflammatory disorders of penis (penis), N48.89 — Other specified disorders of penis (penis, noninfective), N49.1 — Inflammatory disorders of spermatic cord, tunica vaginalis and vas deferens (vas deferens), N49.3 — Fournier gangrene (scrotum), N50.89 — Other specified disorders of the male genital organs (scrotum, noninfective), N76.82 — Fournier disease of vagina and vulva (vulva), O08.0 — Genital tract and pelvic infection following ectopic and molar pregnancy (gas, following, ectopic or molar pregnancy), +15 more

Contextual Map

Every relationship of N45.1 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 N45.1 with this related code in Claim Check

Hierarchy

Referenced by Excludes1 notes

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 12 — Diseases and Disorders of the Male Reproductive System[MDC crossing]: “Diseases and Disorders of the Male Reproductive 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. 1,964 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

  • Didymytis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Epididymitis (acute) (nonvenereal) (recurrent) (residual)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Gangrene, gangrenous (connective tissue) (dropsical) (dry) (moist) (skin) (ulcer), epididymis (infectional)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Periepididymitis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

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 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. "N45.1 — Epididymitis." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/n45.1-epididymitis

Change history

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

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.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to N45.1 in its code family, with their registry titles.

View all codes in the N45 family