2026 ICD-10-CM Diagnosis Code N80.521Superficial endometriosis of the sigmoid colon

ICD-10-CM Codes›N00–N99›N80-N98›N80

ICD-10-CM N80.521
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N80.521 is a billable ICD-10-CM diagnosis code for superficial endometriosis of the sigmoid colon. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Endometriosis.

Code Identity

ICD-10-CM Code
N80.521
Billable Status
Yes — Valid for Submission
Code Describes
Superficial endometriosis of the sigmoid colon
Short Description
Superficial endometriosis of the sigmoid colon
Same as the full description in the CMS dataset.
Parent Code
N80.52
Endometriosis of the sigmoid colon

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN80-N98Noninflammatory disorders of female genital tract
CategoryN80Endometriosis
This CodeN80.521Superficial endometriosis of the sigmoid colon

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
      • colon
        • sigmoid
          • superficial

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 N80.521 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 N80.521Overview

Is N80.521 (Endometriosis of the sigmoid colon) a billable code?

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

What MS-DRG does N80.521 group to?

When superficial endometriosis of the sigmoid colon 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.