2027 ICD-10-CM Diagnosis Code Q04.9Congenital malformation of brain, unspecified
ICD-10-CM Codes›Q00-Q99›Q00-Q07›Q04
- Billable — Valid for Submission
- Risk Adjusts — HCC 182
- POA Exempt
- Chronic Condition
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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 91 through 93, 791, 793. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nervous system congenital anomalies.
For Medicare Advantage risk adjustment, Q04.9 maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries) under the V28 model, adding a risk factor of about 0.478 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Present on Admission (POA)Billing
Q04.9 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Congenital malformations of the nervous system (Q00-Q07).
Medicare Risk Adjustment (HCC)Billing
Q04.9 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- 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
- Mild malformation of cortical development
- 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
- Structural abnormality of Auerbach plexus
- Visceral neuropathy and brain anomaly with facial dysmorphism and developmental delay syndrome
- X-linked cerebral, cerebellar, coloboma syndrome
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q04.9: its own notes plus those printed at Q04 and Chapter 17. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Congenital anomaly NOS of brain
- Congenital deformity NOS of brain
- Congenital disease or lesion NOS of brain
- Multiple anomalies NOS of brain, congenital
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Notes
General instructions on how these codes are used.
- Codes from this chapter are not for use on maternal records
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Anomaly, anomalous (congenital) (unspecified type) Q89.9
brain (multiple) Q04.9
cerebral Q04.9
dura (brain) Q04.9
Cyclencephaly Q04.9
brain (congenital) Q04.9
congenital Q04.9
Disease, diseased See Also: Syndrome;
congenital Q04.9
Malformation (congenital) See Also: Anomaly;
brain (multiple) Q04.9
cerebral Q04.9
brain Q04.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
Code HistoryHistory
Questions About Q04.9Overview
What is the ICD-10 code for congenital malformation of brain, unspecified?
The ICD-10-CM code for congenital malformation of brain, unspecified is Q04.9 (sometimes written as Q049). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
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, 2026 through September 30, 2027.
What MS-DRG does Q04.9 group to?
When congenital malformation of brain, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 91, 92, 93, with relative weights from 0.7783 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
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. The code appears in the Congenital malformations of the nervous system (Q00-Q07) range of the CMS exempt list.
Can Q04.9 be reported with Q87.0?
Not as a rule. The Excludes1 note at Q04, which applies to Q04.9, lists "cyclopia (Q87.0)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is Q04.9?
Q04.9 (congenital malformation of brain, unspecified) maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries), commonly written as HCC 182, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 72 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 155.
Does Q04.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, Q04.9 adds a risk adjustment factor of about 0.478 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.270 to 0.478 depending on the payment segment). A more severe related category (HCC 180, HCC 181, HCC 191, and HCC 192) supersedes it when both are reported. See the full factor table on the HCC 182 category page.
