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Periventricular/intraventricular hemorrhage (P/IVH) is the most common intracranial hemorrhage in premature infants. In the United States, approximately 14,000 very low birth weight (VLBW) infants are diagnosed with P/IVH each year; of these, approximately 7% will develop posthemorrhagic hydrocephalus (PHH). Numerous risk factors for developing P/IVH have been described, most of which are associated with premature birth. Because the majority of babies with P/IVH do not manifest clinical signs, the diagnosis relies on screening with noninvasive cranial imaging. There are no effective neonatal therapies to prevent P/IVH; however, antenatal steroids (ANSs) given to women who are anticipated to deliver preterm reduces the frequency and severity of P/IVH among their offspring. Infants with extensive P/IVH have an increased risk of later neurodevelopmental impairment, whereas those with less-extensive P/IVH may not.
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Since the 1990s, the overall incidence of P/IVH has dramatically decreased from 50% to 20%–25%; however, since the mid-1990s there has been little, if any, progress in reducing the overall incidence further.1,2 This, in part, may be explained by an increase in the birth and survival rates of extremely low birth weight (ELBW) infants (birth weight ≤ 1000 g), the cohort at highest risk for developing not only P/IVH but also the complications associated with PI/VH.3
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Distribution and Frequency
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The site of origin of P/IVH typically is the microcirculation of the subependymal germinal matrix (see the discussion of pathogenesis). The hemorrhage may be isolated or may be accompanied by hemorrhage into the lateral ventricles that may spread throughout the ventricular system, through the foramina of Magendie and Luscka and into the basilar cisterns in the posterior fossa. The particulate matter in the intraventricular blood may obstruct the outflow tracks of the third and fourth ventricles or incite an obliterative arachnoiditis in the posterior fossa with obstruction of cerebrospinal fluid (CSF) flow, resulting in PHH. The reported overall incidence of P/IVH is approximately 20% for infants with a birth weight less than 2000 g and approximately 25% for those who weigh less than 1500 g.
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The most frequently used description of P/IVH was developed in 1978 and demarcated P/IVH into 4 grades: grade I, isolated subependymal hemorrhage (Figure 13-1); grade II, intraventricular hemorrhage (IVH); grade III, IVH with cerebral ventricular dilation (Figure 13-2); and grade IV, parenchymal hemorrhage (Figure 13-3).4 Although the description was intended to characterize findings on computed tomographic brain scans, it continues to be used to describe lesions visualized on cranial ultrasonography (CUS). Isolated subependymal hemorrhage (grade I) is the most common lesion detected (approximately 40% of lesions), while parenchymal hemorrhage (grade IV) is the least frequent (approximately 10% of lesions)2 (Figure 13-4). Since the mid-2000s, the frequency of grade II P/IVH has markedly decreased. The most likely explanation relates to the increasing survival of extremely premature ...