Q04.3 Other reduction deformities of brain

The ICD-10-CM code for Other reduction deformities of brain is Q04.3 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

17: Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0)

Section

Q00-Q07: Congenital malformations of the nervous system (Q00-Q07)

Category Q04

10 codes (9 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to Q04.3:

• Agyria
• Pachygyria
• Microgyria (congenital)
• Hydrancephaly, hydranencephaly
• Lissencephalia, lissencephaly
• Agenesis › cerebellum
• Absence (of) (organ or part) (complete or partial) › cerebellum (vermis)
• Agenesis › vermis of cerebellum

Inclusion Terms

• Absence of part of brain
• Agenesis of part of brain
• Agyria
• Aplasia of part of brain
• Hydranencephaly
• Hypoplasia of part of brain
• Lissencephaly
• Microgyria
• Pachygyria

U.S. Hospital Utilization

• An estimated 5,650 U.S. inpatient stays in 2023 included Q04.3 among the documented diagnoses.
• 75 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

POA indicator for congenital conditions/anomalies and Q00-Q99 exception

Congenital conditions and anomalies Assign “Y” for congenital conditions and anomalies except for categories Q00- Q99, Congenital anomalies, which are on the exempt list. Congenital conditions are always considered present on admission.

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)

Cite This Page

Reference Q04.3 with the canonical source and edition:

Q04.3 — Other reduction deformities of brain. ICD-10 Coding Pro (ICD-10-CM FY2026). https://icd10codingpro.com/codes/Q04.3

Canonical URL: https://icd10codingpro.com/codes/Q04.3