2027 ICD-10-CM Diagnosis Code N45.1Epididymitis

ICD-10-CM Codes›N00–N99›N40-N53›N45

ICD-10-CM N45.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

N45.1 is a billable ICD-10-CM diagnosis code for epididymitis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) 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

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to N45.1: its own notes plus those printed at N45 and Chapter 14. A note printed at a category, block or chapter applies to every code under it.

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 14 (N00-N99) Diseases of the genitourinary system applies to 838 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From N45 Orchitis and epididymitis applies to 4 codes
  • code (B95-B97), to identify infectious agent.

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name N45.1, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming N45.1: they are not reported together with it, unless the two conditions are unrelated.

  • N49 Inflammatory disorders of male genital organs, not elsewhere classified
    orchitis and epididymitis (N45.-) names N45.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About N45.1Overview

What is the ICD-10 code for epididymitis?

The ICD-10-CM code for epididymitis is N45.1 (sometimes written as N451). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

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, 2026 through September 30, 2027.

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 0.8220 to 1.3694 depending on complications. Higher weights mean higher Medicare reimbursement.

Does N45.1 need an additional code?

When the condition applies, yes. The Use Additional Code note at N45, which applies to N45.1, reads: code (B95-B97), to identify infectious agent.. The additional code is reported after N45.1.

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.