2026 ICD-10-CM Diagnosis Code N80.542Deep endometriosis of the appendix

ICD-10-CM Codes›N00–N99›N80-N98›N80

ICD-10-CM N80.542
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N80.542 is a billable ICD-10-CM diagnosis code for deep endometriosis of the appendix. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 391 through 392. Coders also document this condition as deep endometriosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Endometriosis.

Code Identity

ICD-10-CM Code
N80.542
Billable Status
Yes — Valid for Submission
Code Describes
Deep endometriosis of the appendix
Short Description
Deep endometriosis of the appendix
Same as the full description in the CMS dataset.
Parent Code
N80.54
Endometriosis of the appendix

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN80-N98Noninflammatory disorders of female genital tract
CategoryN80Endometriosis
This CodeN80.542Deep endometriosis of the appendix

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Deep endometriosis
  • Deep endometriosis of appendix
  • Endometriosis of appendix
  • Endometriosis of large intestine

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.

    • Endometriosis
      • appendix
        • deep

Clinical ClassificationClinical

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

CCSR GEN019
Endometriosis
Default principal diagnosis: inpatient Yes · outpatient Yes

Code History & ChangesHistory

Replacement N80.542 replaces the following previously assigned code(s):

  • N80.5 - Endometriosis of intestine
FY 2023AddedAdded to the ICD-10-CM code setEffective October 1, 2022.
FY 2024–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About N80.542Overview

Is N80.542 (Endometriosis of the appendix) a billable code?

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

What MS-DRG does N80.542 group to?

When deep endometriosis of the appendix is the principal diagnosis on an inpatient stay, it groups to MS-DRG 391, 392, with relative weights from 0.7796 to 1.2683 depending on complications. Higher weights mean higher Medicare reimbursement.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.