Microcephaly
In Congenital malformations of the nervous system (Q00-Q07), chapter 17: Congenital Malformations, Deformations and Chromosomal Abnormalities
- Q02 is billable and valid on claims for FY 2027. If the record has more detail, check the other codes under Q00-Q07 below.
- As a secondary diagnosis it is not a CC or MCC, so it doesn't raise the MS-DRG payment.
- Counts toward HCC 182 (Spinal Cord Disorders/Injuries) in the Medicare Advantage risk model (CMS-HCC V28).
- AHRQ's Chronic Condition Indicator classes it as chronic: expected to last 12 months or longer and to limit daily life or need ongoing care.
- 50 US deaths in 2024 had an underlying cause in category Q02, per the National Vital Statistics System on CDC WONDER. Death records use WHO ICD-10, so the count is for the whole category.
- Exempt from present-on-admission (POA) reporting. (POA Exempt list)
Also indexed as: Absence, skull bone, with, microcephaly; Agenesis, skull, with, microcephaly; Anomaly, bone, skull, with, microcephaly; Anomaly, skull, with, microcephaly; Deformity, skull, congenital, with, microcephaly; Distortion, skull bone NEC, with, microcephaly; Hydromicrocephaly; Hypoplasia, brain; Hypoplasia, cephalic; Hypoplasia, skull, with, microcephaly; Idiot, microcephalic; Imperfect, closure, skull, with, microcephaly; Micrencephalon; Microcephalus; Microencephalon; Nondevelopment, brain; Oligoencephalon; Undeveloped, brain; Undeveloped, cerebral
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Instructional notes
Includes: conditions that are coded here
- hydromicrocephaly
- micrencephalon
Excludes1: not coded here, use a different code
- Meckel-Gruber syndrome (Q61.9)
Code first: code the underlying condition first, then this code
- if applicable, congenital Zika virus disease
Official coding guidelines
From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.
Assign Q00-QA1 codes for documented congenital anomalies or genetic disorders at any age, coding non-inherent manifestations separately and sequencing Z38 first on the birth admission.
Other codes under Q00-Q07
Congenital malformations of the nervous system (Q00-Q07)
Q02 MS-DRGs
As the principal diagnosis, Q02 groups to MS-DRG 091, 092, 093, 791, or 793 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.
Related conditions
Grouped by AHRQ's Clinical Classifications Software Refined (CCSR), which sorts every diagnosis code into clinically meaningful categories.
Q02 is in Nervous system congenital anomalies (MAL004, its default category), with 50 codes. Others in it:
Medicare coverage articles listing Q02
These 3 Medicare billing and coding articles list Q02 as a diagnosis that supports medical necessity for the services they cover. From the CMS Medicare Coverage Database; check your own contractor's article before billing.
Other codes that refer to Q02
Notes on these codes point to Q02.
About the condition
Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.
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. Parts of the brain may be missing, abnormally small or large, or not fully developed.
Read more about brain malformations on MedlinePlusCode history
Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.
ICD-9-CM equivalent
Legacy crosswalk from the CMS General Equivalence Mappings (last updated 2018).
- 742.1 Microcephalus