2026 ICD-10-CM Diagnosis Code Q04.9Congenital malformation of brain, unspecified

ICD-10-CM Codes›Q00-Q99›Q00-Q07›Q04

ICD-10-CM Q04.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Q04.9 is a billable ICD-10-CM diagnosis code for congenital malformation of brain, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nervous system congenital anomalies.

Code Identity

ICD-10-CM Code
Q04.9
Billable Status
Yes — Valid for Submission
Code Describes
Congenital malformation of brain, unspecified
Short Description
Congenital malformation of brain, unspecified
Same as the full description in the CMS dataset.
Parent Code
Q04
Other congenital malformations of brain

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ00-Q07Congenital malformations of the nervous system
CategoryQ04Other congenital malformations of brain
This CodeQ04.9Congenital malformation of brain, unspecified

Present on Admission (POA)Billing

Q04.9 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.

  • Anomalies of cerebellum
  • Aplasia cutis congenita secondary to malformation syndrome
  • Bilateral renal hypoplasia
  • Brain malformation, congenital heart disease, postaxial polydactyly syndrome
  • Brain malformations, musculoskeletal abnormalities, facial dysmorphism, intellectual disability syndrome
  • BRESEK syndrome
  • Cerebellar cortical dysplasia
  • Cerebro-costo-mandibular syndrome
  • Cerebrofacioarticular syndrome
  • Choreoathetosis
  • CODAS syndrome
  • Combined malformation of central nervous system and skeletal muscle
  • Congenital anomaly of brain
  • Congenital anomaly of cerebrum
  • Congenital atresia of duodenum
  • Congenital brain damage
  • Congenital corneal dystrophy
  • Congenital hypotrichia
  • Congenital labioscrotal agenesis, cerebellar malformation, corneal dystrophy, facial dysmorphism syndrome
  • Congenital muscular hypertrophy-cerebral syndrome
  • Diplegia
  • Disorder of ornithine metabolism
  • Dysplasia with defective mineralization
  • Early-onset epilepsy, intellectual disability, brain anomalies syndrome
  • Endocrine-cerebro-osteodysplasia syndrome
  • Epilepsy due to congenital anomaly of brain
  • Familial visceral neuropathy
  • Focal epilepsy, intellectual disability, cerebro-cerebellar malformation syndrome
  • Global developmental delay, alopecia, macrocephaly, facial dysmorphism, structural brain anomalies syndrome
  • Hypernatremia
  • Intellectual disability, obesity, brain malformation, facial dysmorphism syndrome
  • Left renal hypoplasia
  • Lethal brain and heart developmental defects syndrome
  • Lethal fetal brain malformation, duodenal atresia, bilateral renal hypoplasia syndrome
  • Leukoencephalopathy, thalamus and brainstem anomalies, high lactate syndrome
  • Linear hypopigmentation and craniofacial asymmetry with acral, ocular and brain anomalies
  • Microcephalus, brain defect, spasticity, hypernatremia syndrome
  • Microphthalmia with brain and digit anomaly
  • Microphthalmos due to Delleman syndrome
  • Mitochondrial DNA depletion syndrome hepatocerebrorenal form
  • Multiple brain anomalies
  • Muscle eye brain disease with bilateral multicystic leukodystrophy
  • Oculocerebrocutaneous syndrome
  • Oculocerebrodental syndrome
  • Oculopalatocerebral syndrome
  • Persistent hyperplastic primary vitreous
  • Progressive chorea
  • Right renal hypoplasia
  • Severe oculo-renal-cerebellar syndrome
  • Spastic diplegia
  • Spastic paralysis
  • Visceral neuropathy and brain anomaly with facial dysmorphism and developmental delay syndrome
  • X-linked cerebral, cerebellar, coloboma syndrome

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Congenital anomaly NOS of brain
  • Congenital deformity NOS of brain
  • Congenital disease or lesion NOS of brain
  • Multiple anomalies NOS of brain, congenital

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.

    • Anomaly, anomalous(congenital) (unspecified type)
      • brain (multiple)
    • Anomaly, anomalous(congenital) (unspecified type)
      • cerebral
    • Anomaly, anomalous(congenital) (unspecified type)
      • dura (brain)
    • Cyclencephaly
    • Deformity
      • brain (congenital)
    • Deformity
      • cerebral, acquired
        • congenital
    • Disease, diseased
      • brain
        • congenital
    • Distortion(s) (congenital)
      • brain
    • Lesion(s) (nontraumatic)
      • brain
        • congenital
    • Malformation(congenital)
      • brain (multiple)
    • Malformation(congenital)
      • cerebral
    • Malformation(congenital)
      • dura
        • brain

Clinical ClassificationClinical

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

CCSR MAL004
Nervous system congenital anomalies
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Persistent Hyperplastic Primary Vitreous

    a developmental ocular anomaly in which the primary vitreous body and its surrounding hyaloid vasculature failed to regress. it is usually unilateral and characterized by cataract; microphthalmos (small eyeballs), and retrolenticular fibrovascular tissue. (from yanoff: ophthalmology, 2nd ed.)

  • Hypernatremia

    excessive amount of sodium in the blood. (dorland, 27th ed)

  • Grade 1 Hypernatremia, CTCAE|Grade 1 Hypernatremia

    >uln - 150 mmol/l

  • Grade 2 Hypernatremia, CTCAE|Grade 2 Hypernatremia

    >150 - 155 mmol/l; intervention initiated

  • Grade 3 Hypernatremia, CTCAE|Grade 3 Hypernatremia

    >155 - 160 mmol/l; hospitalization indicated

  • Brachial Amyotrophic Diplegia|BAD|FAS|Flail Arm Syndrome|MIBS|Man-in-barrel Syndrome

    a neurodegenerative condition characterized by asymmetric weakness in the upper extremities resulting from segmental lower motor neuron dysfunction.

  • Diplegia

    paralysis affecting corresponding parts on both sides of the body.

  • Diplegia of Upper Limbs|Diplegia of upper limbs

    evidence of diplegia of the upper limbs.

  • Neurodevelopmental Disorder with Spastic Diplegia and Visual Defects|MRD19|Mental Retardation, Autosomal Dominant 19|NEDSDV

    an autosomal dominant condition caused by mutation(s) in the ctnnb1 gene, encoding catenin beta-1. it is characterized by severe intellectual disability, progressive spastic diplegia, visual impairment, and dysmorphic craniofacial features.

  • Quadriplegia|Bilateral Diplegia|Bilateral Diplegia|Quadriplegia, unspecified|Tetraplegia

    paralysis of all four limbs.

  • Spastic Diplegia|Little's Disease|Spastic diplegic cerebral palsy

    a type of cerebral palsy characterized by spasticity and hypertonia of the lower extremities bilaterally, particularly the legs, hips, and pelvis; this is the most common (70%) form of cerebral palsy.

  • Codas Syndrome

    a rare syndrome caused by mutations in the lonp1 gene. it is characterized by developmental delay, cerebral, ocular, dental, auricular, and skeletal abnormalities.

  • Grade 1 Hypernatremia, CTCAE|Grade 1 Hypernatremia

    >uln-150 mmol/l

  • Grade 2 Hypernatremia, CTCAE|Grade 2 Hypernatremia

    >150-155 mmol/l; intervention initiated

  • Grade 3 Hypernatremia, CTCAE|Grade 3 Hypernatremia

    >155-160 mmol/l; hospitalization indicated

  • Grade 4 Hypernatremia, CTCAE|Grade 4 Hypernatremia

    >160 mmol/l; life-threatening consequences

  • Grade 5 Hypernatremia, CTCAE|Grade 5 Hypernatremia

    death

  • Hypernatremia

    higher than normal levels of sodium in the circulating blood.

  • Hypernatremia, CTCAE|Hypernatremia|Hypernatremia

    a disorder characterized by laboratory test results that indicate an elevation in the concentration of sodium in the blood.

Patient EducationClinical

Brain Malformations

Most brain malformations begin long before a baby is born. Something damages the developing nervous system or causes it to develop abnormally. Sometimes it's a genetic problem. In other cases, exposure to certain medicines, infections, or radiation during pregnancy interferes with brain development.

Read the full article at MedlinePlus

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

Convert Q04.9 to ICD-9-CMHistory

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

ICD-9-CM
742.9 Nervous system anom NOS
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 Q04.9Overview

Is Q04.9 (Other congenital malformations of brain) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report congenital malformation of brain, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is Q04.9 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 congenital malformation of brain, unspecified on inpatient claims.

What is the ICD-9 equivalent of Q04.9?

Under the General Equivalence Mappings, congenital malformation of brain, unspecified converts to ICD-9-CM 742.9 (nervous system anom NOS). 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.