2026 ICD-10-CM Diagnosis Code Q91.0Trisomy 18, nonmosaicism (meiotic nondisjunction)

ICD-10-CM Codes›Q00-Q99›Q90-Q99›Q91

ICD-10-CM Q91.0
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Q91.0 is a billable ICD-10-CM diagnosis code for trisomy 18, nonmosaicism (meiotic nondisjunction). It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is exempt from POA reporting. Coders also document this condition as complete trisomy 18 syndrome. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Chromosomal abnormalities.

Code Identity

ICD-10-CM Code
Q91.0
Billable Status
Yes — Valid for Submission
Code Describes
Trisomy 18, nonmosaicism (meiotic nondisjunction)
Short Description
Trisomy 18, nonmosaicism (meiotic nondisjunction)
Same as the full description in the CMS dataset.
Parent Code
Q91
Trisomy 18 and Trisomy 13

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ90-Q99Chromosomal abnormalities, not elsewhere classified
CategoryQ91Trisomy 18 and Trisomy 13
This CodeQ91.0Trisomy 18, nonmosaicism (meiotic nondisjunction)

Present on Admission (POA)Billing

Q91.0 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Complete trisomy 18 syndrome
  • Trisomy 18 - meiotic nondisjunction
  • Whole chromosome trisomy meiotic nondisjunction

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.

    • Syndrome
      • trisomy
        • 18
          • meiotic nondisjunction
    • Trisomy(syndrome)
      • 18 (partial)
        • meiotic nondisjunction

Clinical ClassificationClinical

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

CCSR MAL009
Chromosomal abnormalities
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Genetic Disorders

Genetic disorders are health conditions caused by changes (also called mutations or variants) in your genes. Genes are parts of DNA found in your cells that carry instructions for how your body grows, develops, and functions. Many genes tell your body how to make proteins, which are needed for your body to work properly.

The full article covers:

  • What are genetic disorders?
  • What causes genetic disorders?
  • What are the types of genetic disorders?
  • What are the different ways a genetic disorder can be inherited?
  • How are genetic disorders diagnosed?

Read the full article at MedlinePlus

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

Convert Q91.0 to ICD-9-CMHistory

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

ICD-9-CM
758.2 Edwards' syndrome
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 Q91.0Overview

Is Q91.0 (Trisomy 18 and Trisomy 13) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report trisomy 18, nonmosaicism (meiotic nondisjunction) on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is Q91.0 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for trisomy 18, nonmosaicism (meiotic nondisjunction) on inpatient claims.

What is the ICD-9 equivalent of Q91.0?

Under the General Equivalence Mappings, trisomy 18, nonmosaicism (meiotic nondisjunction) converts to ICD-9-CM 758.2 (Edwards' syndrome). 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.