2026 ICD-10-CM Diagnosis Code Q91Trisomy 18 and Trisomy 13

ICD-10-CM Codes›Q00-Q99›Q90-Q99›Q91

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

Q91 is a non-billable ICD-10-CM category code for trisomy 18 and Trisomy 13, so it cannot be submitted on claims. Use a more specific code from this category instead, such as Q91.0, Q91.1, Q91.2, and Q91.3.

Code Identity

ICD-10-CM Code
Q91
Billable Status
No — Non-Billable Category
Code Describes
Trisomy 18 and Trisomy 13
Chapter
Q90-Q99
Chromosomal abnormalities, not elsewhere classified

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ90-Q99Chromosomal abnormalities, not elsewhere classified
CategoryQ91Trisomy 18 and Trisomy 13
This CodeQ91Trisomy 18 and Trisomy 13

Specific Coding for Trisomy 18 and Trisomy 13Overview

Non-specific codes like Q91 require more characters. Use one of these billable codes instead:

  • Use Q91.0 for Trisomy 18, nonmosaicism (meiotic nondisjunction)

  • Use Q91.1 for Trisomy 18, mosaicism (mitotic nondisjunction)

  • Use Q91.2 for Trisomy 18, translocation

  • Use Q91.3 for Trisomy 18, unspecified

  • Use Q91.4 for Trisomy 13, nonmosaicism (meiotic nondisjunction)

  • Use Q91.5 for Trisomy 13, mosaicism (mitotic nondisjunction)

  • Use Q91.6 for Trisomy 13, translocation

  • Use Q91.7 for Trisomy 13, unspecified

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.

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 Q91Overview

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

No. This is a category header that groups the codes for trisomy 18 and Trisomy 13, and headers cannot be submitted on claims. Claims for trisomy 18 and Trisomy 13 need a more specific code from this category, such as Q91.0, Q91.1, and Q91.2.