A myelencephalocele is an extremely rare and severe neural tube defect in which a portion of the brain and cerebrospinal fluid herniates through a defect in the skull and skin. It is the most severe form of encephalocele and is almost invariably incompatible with survival. On prenatal ultrasound, a myelencephalocele appears as a large, fluid-filled sac protruding from the fetal head, often with brain tissue visible within the sac. The associated hydrocephalus is usually severe. Pregnancy management in cases of confirmed myelencephalocele typically involves delivery planning at a tertiary center with the expectation that the infant will receive comfort care only, though some rare cases have been attempted surgical repair.
Sonography Term