<unk>  is a bleeding into the subependymal<unk><unk>  with or without subsequent rupture into the lateral ventricle. The microcirculation in this particular area is extremely sensitive to hypoxia and changes in perfusion pressure. It is most frequent before 35 weeks gestation and is typically seen in low birth-weight (<1500g) premature infants.<unk>  <unk>  and intraventricular hemorrhage (IVH) are the most common neurologic injuries in preterm neonates. The brain of a premature infant lacks the ability to autoregulate cerebral blood pressure. Fluctuations in cerebral blood pressure and flow can rupture the primitive<unk><unk>  vessels or lead to infarction of the metabolically active<unk><unk> . The damage can extend into the periventricular white matter, resulting in significant neurologic sequelae, including cerebral palsy, mental retardation, and seizures. A common lesion that characterizes the neuropathology of<unk> /IVH is bleeding into the subependymal<unk><unk> , with or without subsequent rupture into the lateral ventricle. Sequelae of<unk> /IVH include<unk><unk>  destruction, periventricular hemorrhagic infarction with subsequent encephalomalacia], and posthemorrhagic hydrocephalus. Because maturation of the<unk><unk>  vasculature occurs in the perinatal period for premature infants, most cases of<unk> /IVH occur in the first week of life for these infants. Approximately 50% of cases of<unk> /IVH occur in the first day of life. The major risk factors for<unk>  include a young gestational age, low birth weight, acute amnionitis, and exposure to antenatal steroids for less than 48 hours.
Grade 1: Hemorrhage that is confined to the<unk><unk> 
Grade 2: Extension of the hemorrhage into the lateral ventricles without hydrocephalus
Grade 3: Ventricular hemorrhage with the presence of associated hydrocephalus
Grade 4: Parenchymal hemorrhage
US is the primary modality for both screening and follow-up of<unk> /IVH in neonates.
Acute subependymal hemorrhage appears as a homogeneous echogenic mass, often in the caudothalamic groove. The hematoma becomes less echogenic over time, beginning with the central portion. Subsequent to eventual clot retraction, a subependymal cyst may develop, or a linear echo may result.
Acutely, IVH also appears echogenic. Cerebrospinal fluid (CSF)–blood fluid levels may be observed. When large, the clot forms a cast of the ventricle.
Germinal matrix hemorrhage
Tooth fusion
Schizencephaly
Extra-axial hemorrhage
Agenesis of the corpus callosum
Cavum septum pellucidum
Megalencephaly
Lissencephaly