DxCodebookFY2027 · Oct 1, 2026 – Sep 30, 2027

Category · FY2027

Q04 Other congenital malformations of brain

  • Header · not billable

Q04 is not billable. The category heads 9 billable codes in FY2027: the 9 codes directly below it.

Index → code

Where it sits

  1. Chapter 17 Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA1)
  2. Q00-Q07 Congenital malformations of the nervous system (Q00-Q07)
  3. Q04 Other congenital malformations of brain
Billable codes
9
Subdivisions
9
CC / MCC codes
4 / 4
HCC V28 codes
9
New FY2027
0
Index entries
65

Codes in Q04

  1. Q04.0
    Congenital malformations of corpus callosum
    BillableMCC182Exempt
    Inclusion terms 1

    Inclusion terms

    • Agenesis of corpus callosum
  2. Q04.1
    Arhinencephaly
    BillableMCC182Exempt
  3. Q04.2
    Holoprosencephaly
    BillableMCC182Exempt
  4. Q04.3
    Other reduction deformities of brain
    BillableMCC182Exempt
    Inclusion terms 9, Excludes1 1

    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

    Excludes1

    • congenital malformations of corpus callosum (Q04.0) Q04.0
  5. Q04.4
    Septo-optic dysplasia of brain
    BillableCC182Exempt
  6. Q04.5
    Megalencephaly
    BillableCC182Exempt
  7. Q04.6
    Congenital cerebral cysts
    BillableCC182Exempt
    Inclusion terms 2, Excludes1 1

    Inclusion terms

    • Porencephaly
    • Schizencephaly

    Excludes1

    • acquired porencephalic cyst (G93.0) G93.0
  8. Q04.8
    Other specified congenital malformations of brain
    BillableCC182Exempt
    Inclusion terms 2

    Inclusion terms

    • Arnold-Chiari syndrome, type IV
    • Macrogyria
  9. Q04.9
    Congenital malformation of brain, unspecified
    Billable182Exempt
    Inclusion terms 4

    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

CC/MCC: as a secondary diagnosis, unless the principal diagnosis is on the code’s PDX exclusion list (MS-DRG v44 Appendix C; list on the code card).

Sources of each column.

Instructions

At Q04

Excludes1

Notes that also apply

Chapter 17 instructions (Notes 1, Excludes2 1): printed on the chapter 17 page.

Index entries

  • Arhinencephaly → Q04.1
  • Holoprosencephaly → Q04.2
  • Agyria → Q04.3
  • Hydrancephaly, hydranencephaly → Q04.3
  • Lissencephalia, lissencephaly → Q04.3
  • Microgyria (congenital) → Q04.3
  • Pachygyria → Q04.3
  • Hemimegalencephaly → Q04.5
  • Megalencephaly → Q04.5
  • Porencephaly (congenital) (developmental) (true) → Q04.6
  • Schizencephaly → Q04.6
  • Macrogyria (congenital) → Q04.8
  • Ulegyria → Q04.8
  • Cyclencephaly → Q04.9
  • Absence (of) (organ or part) (complete or partial)corpus callosum → Q04.0
  • Agenesiscorpus callosum → Q04.0
  • Aplasiacorpus callosum → Q04.0
  • Hypoplasia, hypoplasticcorpus callosum → Q04.0
  • Malformation (congenital)corpus callosum (congenital) → Q04.0
  • Absence (of) (organ or part) (complete or partial)cerebellum (vermis) → Q04.3
  • Agenesiscerebellum → Q04.3
  • Agenesisvermis of cerebellum → Q04.3
  • Aplasiacerebellum → Q04.3
  • Hypoplasia, hypoplasticcerebellum → Q04.3
  • Dysplasiasepto-optic → Q04.4
  • Cyst (colloid) (mucous) (simple) (retention)paraphysis, cerebri, congenital → Q04.6
  • Cyst (colloid) (mucous) (simple) (retention)porencephalic → Q04.6
  • Arnold-Chiari disease, obstruction or syndrome (type II)type IV → Q04.8
  • Displacement, displacedbrain stem, caudal (congenital) → Q04.8
  • Displacement, displacedcerebellum, caudal (congenital) → Q04.8
  • Distortion(s) (congenital)gyri → Q04.8
  • Ectopic, ectopia (congenital)brain → Q04.8
  • Ectopic, ectopia (congenital)cerebral → Q04.8
  • Heterotopia, heterotopiccerebralis → Q04.8
  • Anomaly, anomalous (congenital) (unspecified type)brain (multiple) → Q04.9
  • Anomaly, anomalous (congenital) (unspecified type)cerebral → Q04.9
  • Anomaly, anomalous (congenital) (unspecified type)dura (brain) → Q04.9
  • Deformitybrain (congenital) → Q04.9
  • Distortion(s) (congenital)brain → Q04.9
  • Malformation (congenital)brain (multiple) → Q04.9

25 more, longer entries are not listed; the search box finds them by word.

NCHS Alphabetic Index. Index first, then the Tabular List.

Hierarchy