2026 ICD-10-CM Diagnosis Code N45.1Epididymitis

ICD-10-CM Codes›N00–N99›N40-N53›N45

ICD-10-CM N45.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N45.1 is a billable ICD-10-CM diagnosis code for epididymitis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 727 through 728. Coders also document this condition as acute epididymitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Inflammatory conditions of male genital organs.

Code Identity

ICD-10-CM Code
N45.1
Billable Status
Yes — Valid for Submission
Code Describes
Epididymitis
Short Description
Epididymitis
Same as the full description in the CMS dataset.
Parent Code
N45
Orchitis and epididymitis

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN40-N53Diseases of male genital organs
CategoryN45Orchitis and epididymitis
This CodeN45.1Epididymitis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute epididymitis
  • Chronic epididymitis
  • Epididymitis
  • Epididymitis associated with another disorder
  • Epididymitis without abscess
  • Infective epididymitis
  • Spermatogenic granuloma
  • Spermatogenic granuloma of epididymis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Didymytis
    • Epididymitis(acute) (nonvenereal) (recurrent) (residual)
    • Gangrene, gangrenous(connective tissue) (dropsical) (dry) (moist) (skin) (ulcer)
      • epididymis (infectional)
    • Periepididymitis

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR GEN013
Inflammatory conditions of male genital organs
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Epididymitis

    inflammation of the epididymis. its clinical features include enlarged epididymis, a swollen scrotum; pain; pyuria; and fever. it is usually related to infections in the urinary tract, which likely spread to the epididymis through either the vas deferens or the lymphatics of the spermatic cord.

Patient EducationClinical

Testicular Disorders

Testicles, or testes, make male hormones and sperm. They are two egg-shaped organs inside the scrotum, the loose sac of skin behind the penis. It's easy to injure your testicles because they are not protected by bones or muscles. Men and boys should wear athletic supporters when they play sports.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert N45.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
604.90 Orchitis/epididymit NOS
Approximate The match is approximate rather than exact.
ICD-9-CM
604.99 Orchitis/epididymit NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About N45.1Overview

Is N45.1 (Orchitis and epididymitis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report epididymitis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does N45.1 group to?

When epididymitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 727, 728, with relative weights from 0.8112 to 1.4829 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of N45.1?

Under the General Equivalence Mappings, epididymitis converts to ICD-9-CM 604.90 (orchitis/epididymit NOS) and 604.99 (orchitis/epididymit NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.