ICD-10-CM 2027 diagnosis code

Q91Trisomy 18 and Trisomy 13

Not billable — use a more specific code

Q91 is a header code, so it can't be reported by itself. Choose one of the 8 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About Q91

Q91 is the ICD-10-CM diagnosis code for trisomy 18 and Trisomy 13. It belongs to block Q90-Q99 (chromosomal abnormalities, not elsewhere classified) and chapter 17 (congenital malformations, deformations, chromosomal abnormalities, and genetic disorders). It is a header code, so it can't be reported by itself; one of its 8 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: Q91.0 (nondisjunction)), Q91.1 (nondisjunction)), Q91.2 (translocation), Q91.3 (unspecified), Q91.4 (nondisjunction)), Q91.5 (nondisjunction)), Q91.6 (translocation) and Q91.7 (unspecified).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under Q91

Notes that apply from higher levels

Instructions written at a parent level also apply to Q91.

Broader instructions also apply from Q90-Q99 Chromosomal abnormalities, not elsewhere classified and Chapter 17: Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders.

Codes whose notes reference Q91

Q92Excludes1

Code history

2016
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2018
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2020
2021
2022
2023
2024
2025
2026
2027

FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
No changes since FY2016.

Common questions about Q91

Is Q91 billable?: No. Q91 is a header code. Report one of its more specific subcodes instead.