2026 ICD-10-CM Diagnosis Code N91.5Oligomenorrhea, unspecified
ICD-10-CM Codes›N00–N99›N80-N98›N91
- Billable — Valid for Submission
- Chronic Condition
N91.5 is a billable ICD-10-CM diagnosis code for oligomenorrhea, unspecified. 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 finding of frequency of menstruation. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Menstrual disorders.
Code Identity
Code Classification
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
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Hypomenorrhea NOS
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
- Oligomenorrhea - N91.5
External Cause of Injuries IndexGuidance
References for this code in the External Cause of Injuries Index.
- Oligomenorrhea
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Oligomenorrhea
abnormally infrequent menstruation.Oligomenorrhea
infrequent menstrual periods.Hypomenorrhea
decreased menstrual blood flow.
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
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Convert N91.5 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About N91.5Overview
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, 2025 through September 30, 2026.
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 0.5696 to 1.8348 depending on complications. Higher weights mean higher Medicare reimbursement.
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.
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.
