2027 ICD-10-CM Diagnosis Code N91.5Oligomenorrhea, unspecified

ICD-10-CM Codes›N00–N99›N80-N98›N91

ICD-10-CM N91.5
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

N91.5 is a billable ICD-10-CM diagnosis code for oligomenorrhea, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 742 through 743, 760 through 761. Coders also document this condition as finding of frequency of menstruation. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Menstrual disorders.

Code Identity

ICD-10-CM Code
N91.5
Billable Status
Yes — Valid for Submission
Code Describes
Oligomenorrhea, unspecified
Short Description
Oligomenorrhea, unspecified
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 CodeN91.5Oligomenorrhea, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Finding of frequency of menstruation
  • Hypomenorrhea
  • Light and infrequent menstruation
  • Mid-cycle bleeding
  • Oligomenorrhea
  • Oligoovulatory dysfunctional uterine bleeding
  • Ovulation bleeding

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to N91.5: its own notes plus those printed at N91 and Chapter 14. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Hypomenorrhea NOS

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From N91 Absent, scanty and rare menstruation applies to 6 codes
  • ovarian dysfunction (E28.-)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 14 (N00-N99) Diseases of the genitourinary system applies to 838 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name N91.5, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming N91.5: they are not reported together with it, unless the two conditions are unrelated.

  • N92.6 Irregular menstruation, unspecified
    lengthened intervals or scanty bleeding (N91.3-N91.5) names N91.3-N91.5, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

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

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

Clinical InformationClinical

  • Oligomenorrhea

    abnormally infrequent menstruation.

Patient EducationClinical

Menstruation

Menstruation, also called a period, is normal vaginal bleeding that happens as part of the monthly cycle in women and girls. Every month, the body prepares for pregnancy. If pregnancy does not happen, the uterus (womb) sheds its lining. This blood and tissue leave the body through the vagina.

The full article covers:

  • What is menstruation?
  • What is the menstrual cycle?
  • When will my period start?
  • What are the symptoms of menstruation?
  • What are menstrual irregularities?

Read the full article at MedlinePlus

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

Convert N91.5 to ICD-9-CMHistory

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

ICD-9-CM
626.1 Scanty 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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About N91.5Overview

What is the ICD-10 code for oligomenorrhea, unspecified?

The ICD-10-CM code for oligomenorrhea, unspecified is N91.5 (sometimes written as N915). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is N91.5 (Absent, scanty and rare menstruation) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report oligomenorrhea, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does N91.5 group to?

When oligomenorrhea, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 742, 743, 760, 761, with relative weights from 0.7039 to 1.8448 depending on complications. Higher weights mean higher Medicare reimbursement.

Can N91.5 be reported with a code from E28?

Not as a rule. The Excludes1 note at N91, which applies to N91.5, lists "ovarian dysfunction (E28.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

What is the ICD-9 equivalent of N91.5?

Under the General Equivalence Mappings, oligomenorrhea, unspecified converts to ICD-9-CM 626.1 (scanty menstruation). The mapping is approximate, so confirm the match fits the documentation.