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ICD-10-CM 2027 diagnosis code

N80.321Superficial endometriosis of the posterior cul-de-sac

✓ Billable / specificFemale only

N80.321 is a valid, billable ICD-10-CM code for superficial endometriosis of the posterior cul-de-sac. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code last changed in FY2023 (effective October 1, 2022). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About N80.321

N80.321 is the ICD-10-CM diagnosis code for superficial endometriosis of the posterior cul-de-sac. It belongs to category N80 (endometriosis), block N80-N98 (noninflammatory disorders of female genital tract) and chapter 14 (diseases of the genitourinary system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within N80.32 (endometriosis of the posterior cul-de-sac), N80.321 is specifically for superficial endometriosis of the posterior cul-de-sac. Related codes cover deep endometriosis of the posterior cul-de-sac (N80.322) and unspecified depth (N80.329).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 742 (Uterine and Adnexa Procedures for Non-Malignancy with CC/MCC, relative weight 1.8456), DRG 743 (Uterine and Adnexa Procedures for Non-Malignancy without CC/MCC, relative weight 1.2974), DRG 760 (Menstrual and Other Female Reproductive System Disorders with CC/MCC, relative weight 1.0129) and DRG 761 (Menstrual and Other Female Reproductive System Disorders without CC/MCC, relative weight 0.7041), in MDC 13 (Diseases and Disorders of the Female Reproductive System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It is on the CMS list of diagnoses consistent only with female patients (the sex-conflict edit itself was retired in FY2025).

It was added in FY2023, effective October 1, 2022.

Notes that apply from higher levels

Instructions written at a parent level also apply to N80.321.

Broader instructions also apply from Chapter 14: Diseases of the genitourinary system.

Alphabetic index entries

1 entries

Terms in the official ICD-10-CM index that lead to N80.321.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2023 (effective 10/1/2022): Added
  • No changes since FY2023.

Common questions about N80.321

Is N80.321 billable?

Yes. N80.321 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can N80.321 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict N80.321 as a principal diagnosis.

Is N80.321 a CC or MCC?

No. N80.321 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does N80.321 group to?

N80.321 is used in the MS-DRG v44.0 logic for MS-DRG 742 (Uterine and Adnexa Procedures for Non-Malignancy with CC/MCC), MS-DRG 743 (Uterine and Adnexa Procedures for Non-Malignancy without CC/MCC), MS-DRG 760 (Menstrual and Other Female Reproductive System Disorders with CC/MCC) and MS-DRG 761 (Menstrual and Other Female Reproductive System Disorders without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.