Microcephaly (Q02) ICD-10-CM
The Q02 code range covers microcephaly with 1 ICD-10-CM diagnosis codes. 1 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Includes
This note appears immediately under a three character code title to further define, or give examples of, the content of the category.
- hydromicrocephaly
- micrencephalon
Code First
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
- , if applicable, congenital Zika virus disease
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
- Meckel-Gruber syndrome Q61.9
Codes in the Q02 Range 1 codes · 1 billable
- Q02 Microcephaly
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the Q02 range.
Cerebrum
Derived from TELENCEPHALON, cerebrum is composed of a right and a left hemisphere. Each contains an outer cerebral cortex and a subcortical basal ganglia. The cerebrum includes all parts within the skull except the MEDULLA OBLONGATA, the PONS, and the CEREBELLUM. Cerebral functions include sensorimotor, emotional, and intellectual activities.
Hydranencephaly
A congenital condition where the greater portions of the cerebral hemispheres and CORPUS STRIATUM are replaced by CSF and glial tissue. The meninges and the skull are well formed, which is consistent with earlier normal embryogenesis of the telencephalon. Bilateral occlusions of the internal carotid arteries in utero is a potential mechanism. Clinical features include intact brainstem reflexes without evidence of higher cortical activity. (Menkes, Textbook of Child Neurology, 5th ed, p307)
Hypernatremia
Excessive amount of sodium in the blood. (Dorland, 27th ed)
Insulin Resistance
Diminished effectiveness of INSULIN in lowering blood sugar levels: requiring the use of 200 units or more of insulin per day to prevent HYPERGLYCEMIA or KETOSIS.
Metabolic Syndrome
A cluster of symptoms that are risk factors for CARDIOVASCULAR DISEASES and TYPE 2 DIABETES MELLITUS. The major components of metabolic syndrome include ABDOMINAL OBESITY; atherogenic DYSLIPIDEMIA; HYPERTENSION; HYPERGLYCEMIA; INSULIN RESISTANCE; a proinflammatory state; and a prothrombotic (THROMBOSIS) state.
Microcephaly
A congenital abnormality in which the CEREBRUM is underdeveloped, the fontanels close prematurely, and, as a result, the head is small. (Desk Reference for Neuroscience, 2nd ed.)
Nijmegen Breakage Syndrome
A chromosome instability syndrome resulting from a defective response to DNA double-strand breaks. In addition to characteristic FACIES and MICROCEPHALY, patients have a range of findings including RADIOSENSITIVITY, immunodeficiency, increased cancer risk, and growth retardation. Causative mutations occur in the NBS1 gene, located on human chromosome 8q21. NBS1 codes for nibrin, the key regulator protein of the R/M/N (RAD50/MRE11/NBS1) protein complex which senses and mediates cellular response to DNA DAMAGE caused by IONIZING RADIATION.
About the Q02 Code Range
ICD-10 code Q02 is used to classify microcephaly, a congenital condition characterized by an abnormally small head size caused by atypical brain development. This code specifically captures various forms of microcephaly diagnosed at or shortly after birth.
Microcephaly, also known as congenital microcephaly or microencephaly, includes a range of related syndromes such as microcephaly with simplified gyral pattern or microlissencephaly, and is often associated with intellectual disability, developmental delays, seizures, and other neurological impairments. The ICD-10 code Q02 covers a broad spectrum of microcephaly presentations, including those linked with specific syndromes involving facial dysmorphism, muscle weakness, eye abnormalities, and genetic disorders. This code is essential for healthcare professionals and medical coders to accurately document and differentiate microcephaly from other nervous system congenital anomalies, ensuring precise reporting for clinical care and epidemiological tracking.
Questions About This Page
How many billable codes are in the Q02 range?
Of the 1 codes in this range, 1 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the Q02 range classify?
The range classifies microcephaly. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
