Female, 26 years old, 31 weeks gestational age with holoprosencephaly suspected on ultrasound. A generalized failure of midline brain separation is evident. Cerebral parenchyma is underdeveloped and represented predominantly by a smooth cortical mantle which spans both sides of the cranium. A rudimentary interhemispheric fissure is seen anteriorly and inferiorly, but the interhemispheric fissure is largely absent elsewhere.The cortical mantle enwraps a single monoventricle. The thalami are fused. Posterior fossa structures are relatively unremarkable. No evidence to suggest intracranial hemorrhage is seen.The left fetal globe appears to be normally formed. The right fetal globe is either absent or hypoplastic and malformed, though the bony orbit does seem to be present. A normally positioned nose appears to be present.A subjective overabundance of amniotic fluid is seen. Prominence of the left maternal renal collecting system is likely physiologic.
Constellation of findings compatible with alobar holoprosencephaly.