Holoprosencephaly

This code represents a severe congenital brain malformation characterized by the failure of the prosencephalon (the embryonic forebrain) to divide into two cerebral hemispheres. This results in a single, undivided brain ventricle and varying degrees of facial anomalies, often including cyclopia, proboscis, or cleft lip/palate. The severity ranges from alobar (most severe) to semilobar and lobar (least severe) forms.

Use this code when documentation clearly indicates a diagnosis of holoprosencephaly, typically identified prenatally via ultrasound or MRI, or postnatally through clinical examination and neuroimaging. This code is appropriate for reporting the primary diagnosis in infants or fetuses with this condition. Documentation should specify the type if known, though this code covers all forms.

• Do not confuse this with other congenital hydrocephalus codes; holoprosencephaly involves a failure of brain division, not just fluid accumulation.
• Always review documentation for associated anomalies (e.g., facial dysmorphism, chromosomal abnormalities) and code them separately if present.
• This code is often a primary diagnosis for neonates with this condition and may be sequenced before codes for symptomatic manifestations.