2026 ICD-10-CM Diagnosis Code N80.121Deep endometriosis of right ovary

ICD-10-CM Codes›N00–N99›N80-N98›N80

ICD-10-CM N80.121
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N80.121 is a billable ICD-10-CM diagnosis code for deep endometriosis of right ovary. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 742 through 743, 760 through 761. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Endometriosis.

Code Identity

ICD-10-CM Code
N80.121
Billable Status
Yes — Valid for Submission
Code Describes
Deep endometriosis of right ovary
Short Description
Deep endometriosis of right ovary
Same as the full description in the CMS dataset.
Parent Code
N80.12
Deep endometriosis of ovary

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN80-N98Noninflammatory disorders of female genital tract
CategoryN80Endometriosis
This CodeN80.121Deep endometriosis of right ovary

Clinical ClassificationClinical

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

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

Patient EducationClinical

Endometriosis

The uterus, or womb, is the place where a fetus grows during pregnancy. The uterus is lined with tissue (endometrium). Endometriosis is a disease in which tissue like the lining of the uterus grows in other places in your body. These patches of tissue are called "implants," "nodules," or "lesions." They are most often found:

The full article covers:

  • What is endometriosis?
  • What causes endometriosis?
  • Who is at risk for endometriosis?
  • What are the symptoms of endometriosis?
  • How is endometriosis diagnosed?
  • What are the treatments for endometriosis?

Read the full article at MedlinePlus

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

Code History & ChangesHistory

Replacement N80.121 replaces the following previously assigned code(s):

  • N80.1 - Endometriosis of ovary
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 N80.121Overview

Is N80.121 (Deep endometriosis of ovary) a billable code?

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

What MS-DRG does N80.121 group to?

When deep endometriosis of right ovary is the principal diagnosis on an inpatient stay, it groups to MS-DRG 742, 743, 760, 761, with relative weights from 0.5696 to 1.8348 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.