2026 ICD-10-CM Diagnosis Code N91.0Primary amenorrhea

ICD-10-CM Codes›N00–N99›N80-N98›N91

ICD-10-CM N91.0
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N91.0 is a billable ICD-10-CM diagnosis code for primary amenorrhea. 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. Coders also document this condition as menstrual period late. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Menstrual disorders.

Code Identity

ICD-10-CM Code
N91.0
Billable Status
Yes — Valid for Submission
Code Describes
Primary amenorrhea
Short Description
Primary amenorrhea
Same as the full description in the CMS dataset.
Parent Code
N91
Absent, scanty and rare menstruation

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN80-N98Noninflammatory disorders of female genital tract
CategoryN91Absent, scanty and rare menstruation
This CodeN91.0Primary amenorrhea

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Menstrual period late
  • Physiologic amenorrhea
  • Primary amenorrhea
  • Primary physiologic amenorrhea

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.

    • Amenorrhea
      • primary
    • Delay, delayed
      • menstruation (cause unknown)
    • Failure, failed
      • menstruation at puberty
    • Menstruation
      • delayed

Clinical ClassificationClinical

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

CCSR GEN021
Menstrual disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Menstruation

Menstruation, or period, is normal vaginal bleeding that occurs as part of a woman's monthly cycle. Every month, your body prepares for pregnancy. If no pregnancy occurs, the uterus, or womb, sheds its lining. The menstrual blood is partly blood and partly tissue from inside the uterus. It passes out of the body through the vagina.

Read the full article at MedlinePlus

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

Convert N91.0 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
626.0 Absence of menstruation
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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About N91.0Overview

Is N91.0 (Absent, scanty and rare menstruation) a billable code?

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

What MS-DRG does N91.0 group to?

When primary amenorrhea 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.

What is the ICD-9 equivalent of N91.0?

Under the General Equivalence Mappings, primary amenorrhea converts to ICD-9-CM 626.0 (absence of menstruation). The mapping is approximate, so confirm the match fits the documentation.

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.