Prenatal brain damage and placental infarction--an autopsy study

Periventricular hemorrhagic infarction in preterm neonates: Etiology and time of development

BACKGROUND

To find the obstetrical and delivery associated risk factors of antenatal and postnatal grade III intraventricular hemorrhage (IVH) or periventricular hemorrhagic infarction (PVHI) in preterm neonates.

METHODS

A retrospective study of obstetric and delivery associated risk factors included neonates (<35 gestational weeks) with severe IVH/PVHI (n = 120) and a prospectively collected control group (n = 50). The children were divided into: (1) antenatal onset group (n = 27) with insult visible on cerebral ultrasonography within the first 12 hours of birth or periventricular cystic changes visible in PVHI within the first 3 days; (2) neonatal onset group (n = 70) with insult diagnosed after initial normal findings or I-II grade IVH, and (3) unknown time-onset group (n = 23) with insult visible at > 12 h of age.

RESULTS

The mothers of the antenatal onset group had significantly more bacterial infections before delivery compared to the neonatal onset group: 20/27 (74.1%) versus 23/69 (33.3%), (odds ratio (OR) 5.7 [95% confidence interval 2.1-16]; p = 0.0008) or compared to the control group (11/50 (22%); OR 11 [2.8-42]; p = 0.0005). Placental histology revealed chorioamnionitis more often in the antenatal compared to the neonatal onset group (14/21 (66.7%) versus 16/42 (38.1%), respectively; OR 3.7 [1.18-11]; p = 0.025). Neonates with neonatal development of severe IVH/PVHI had significantly more complications during delivery or intensive care.

CONCLUSIONS

Bacterial infection during pregnancy is an important risk factor for development of antenatal onset severe IVH or PVHI. In neonates born to mothers with severe bacterial infection during pregnancy, cerebral ultrasonography is indicated for early detection of severe IVH or PVHI.

Placental Pathology and the Developing Brain

Abnormal neurodevelopmental outcomes are associated with multiple factors including prematurity, intrauterine infection, maternal comorbidities as well as fetal anomalies. Within the past decade, new standardized terminology in placental pathology has emerged, emphasizing the current understanding of processes that play a role in placental dysfunction. Factors playing a major role in the abnormal development of the placenta include abnormalities in blood flow and perfusion of the fetal and maternal compartments of the placenta termed fetal vascular malperfusion and maternal vascular malperfusion, respectively. Concepts reviewed include massive perivillous fibrin deposition, chronic villitis, meconium-associated injury as well as chorioamnionitis. Each have a temporal effect on the placental vascular tree and may reflect an altered maternal inflammatory response. In this article we highlight pathologic placental findings which when present can serve to explain, at least in part, altered neurodevelopment in the child, adolescent and adult. Lesions with a propensity for recurrence in future pregnancies are discussed.

Placental pathology: Pathways leading to or associated with perinatal brain injury in experimental neurology, special issue: Placental mediated mechanisms of perinatal brain injury

Perinatal brain injury is a multifactorial process. In utero placental physiology plays a major role in neuroprotection and the normal development of the fetal central nervous system. Advances in placental pathology have clarified several specific mechanisms of injury and the histologic lesions most strongly associated with them. This review provides an updated summary of the relevant placental anatomy and physiology, the specific placental pathways leading to brain injury, the revised Amsterdam classification system for placental pathology, and the known associations of specific placental lesions with subtypes of adverse neurologic outcomes.

Placental contribution to neonatal encephalopathy

Placental assessment, although currently underused, can inform our understanding of the etiology and timing of Neonatal Encephalopathy (NE). We review our current understanding of the links between placental dysfunction and NE and how this information may inform clinical decisions, now and in the future, emphasizing the four major placental lesions associated with NE. In addition, we discuss maternal and fetal factors that are hypothesized to contribute to specific placental pathologies, especially innate or acquired thrombophilias. We outline the importance of assessing placenta across trimesters and after delivery. As this field continues to evolve, currently available placental histopathological examination methods may need to be combined with advanced prenatal molecular and imaging assessments of placenta and be applied in well-designed studies in large representative populations to better define the links between placental dysfunction and NE.

Delayed Fulminant Hepatic Failure from Dydrogesterone-Related In Vitro Fertilization Therapy Requiring Liver Transplantation During Pregnancy

Patient: Female, 35-year-old

Final Diagnosis: Fulminant liver failure

Symptoms: Coagulopathy • hepatic encephalopathy • jaundice

Medication:—

Clinical Procedure: Liver transplantation

Specialty: Gastroenterology and Hepatology

Placental infarcts in the collaborative perinatal project: Variable associations infer variable constructs

PURPOSE

Reproducible diagnoses of placental infarcts may permit more accurate assessment of their clinical significance. Using data across the 12 study sites of the National Collaborative Perinatal Project, we investigated the consistency of associations between infarct features with birthweight, placental weight and measures of placental "efficiency."

METHODS

All delivered infants, live or stillborn, single or multiple, regardless of gestational age, were included. Pathologists scored infarcts by color (tan-white or "old" or pink-red "more recent"), size (cm), location (marginal or central), and total number.

RESULTS

Incidence of any infarcts and distributions of specific features such as size, color (indicating age), locations and total numbers of infarcts were highly variable across sites, as were their associations with birthweight and placental efficiency. The most stable associations (consistent results across sites) of placental infarct scores were with placental size and/or other placental shape variables and with birthweight, but the number of significant associations ranged from 13 to 1.

CONCLUSION

Given the extremes of infarct incidence within each site plus the variable correlations of infarct features with other placental and birth outcome measures, CPP infarct scores cannot be used as indicative of an underlying shared pathophysiologic construct. However, given the accumulating evidence that intrauterine stressors have the potential for lifelong impact on health, we propose that the infarct features and distinctions proposed are neither complex nor should they be jettisoned. Rather these measures should be clarified and refined. Only then can we understand the reported associations of placental infarcts with child and adult health outcomes.

Motor vehicle crashes during pregnancy and cerebral palsy during infancy: a longitudinal cohort analysis

OBJECTIVES

To assess the incidence of cerebral palsy among children born to mothers who had their pregnancy complicated by a motor vehicle crash.

DESIGN

Retrospective longitudinal cohort analysis of children born from 1 April 2002 to 31 March 2012 in Ontario, Canada.

PARTICIPANTS

Cases defined as pregnancies complicated by a motor vehicle crash and controls as remaining pregnancies with no crash.

MAIN OUTCOME

Subsequent diagnosis of cerebral palsy by age 3 years.

RESULTS

A total of 1 325 660 newborns were analysed, of whom 7933 were involved in a motor vehicle crash during pregnancy. A total of 2328 were subsequently diagnosed with cerebral palsy, equal to an absolute risk of 1.8 per 1000 newborns. For the entire cohort, motor vehicle crashes correlated with a 29% increased risk of subsequent cerebral palsy that was not statistically significant (95% CI -16 to +110, p=0.274). The increased risk was only significant for those with preterm birth who showed an 89% increased risk of subsequent cerebral palsy associated with a motor vehicle crash (95% CI +7 to +266, p=0.037). No significant increase was apparent for those with a term delivery (95% CI -62 to +79, p=0.510). A propensity score-matched analysis of preterm births (n=4384) yielded a 138% increased relative risk of cerebral palsy associated with a motor vehicle crash (95% CI +27 to +349, p=0.007), equal to an absolute increase of about 10.9 additional cases per 1000 newborns (18.2 vs 7.3, p=0.010).

CONCLUSIONS

Motor vehicle crashes during pregnancy may be associated with an increased risk of cerebral palsy among the subgroup of cases with preterm birth. The increase highlights a specific role for traffic safety advice in prenatal care.

Placental pathology is associated with severity of neonatal encephalopathy and adverse developmental outcomes following hypothermia

OBJECTIVE

Although neonatal encephalopathy (NE) due to perinatal asphyxia accounts for a notable proportion of brain injury, the causal pathway remains largely unexplained. We sought to determine the association of placental pathology with: (1) severity of NE in the first 6 hours postnatal, and (2) abnormal neurodevelopmental outcomes (NDO) in neonates requiring hypothermia therapy.

STUDY DESIGN

This is a retrospective cohort study of neonates ≥36 weeks' gestation born at Parkland Hospital, Dallas, TX, from January 2006 through November 2011 with NE. Placental histology was reviewed and validated by a pediatric pathologist blinded to outcomes. Abnormal NDO was defined as death or Bayley-III score of <85 at 18-24 months of age.

RESULTS

Of 86,274 neonates ≥36 weeks' gestation, 120 had evidence of a combination of perinatal acidosis and NE. In all, 47 had mild NE and received no treatment, while 73 had moderate (n = 70) or severe (n = 3) NE and received systemic hypothermia. Nine neonates died and all survivors receiving hypothermia had a Bayley-III assessment at 22 ± 7 (SD) months of age. Chorioamnionitis with or without fetal response and patchy/diffuse chronic villitis were found to be independently associated with severity of NE (P < .001). Univariate logistic regression revealed an association with a diagnosis of major placental pathology (odds ratio, 3.5; 95% confidence interval, 1.1-11.4) and abnormal outcomes following cooling. Specifically, diffuse chronic villitis (odds ratio, 9.29; 95% confidence interval, 1.11-77.73) was the only individual predictor of abnormal NDO following hypothermia therapy.

CONCLUSION

Placental inflammatory villitis appears to be a harbinger of abnormal outcomes in neonates with NE, spanning to the 18-24 month NDO.

Acute thymic involution in unexplained third trimester stillbirth: frequency, grade, and correlation with neuropathologic injury

Many 3rd-trimester stillbirths are unexplained, including the time course of the illness. Histologic acute thymic involution (ATI), when graded, correlates with duration of acute illness (grade 0, <12 hours; grade 4, >72 hours). Histologic brain injury is also common in stillbirth. We investigated ATI in unexplained stillbirth and correlated it with neuropathologic injury by identifying 58 autopsies of unexplained, 3rd-trimester stillborns (preterm, n  =  24; term, n  =  34) that included brain examination and graded ATI from 0 (resting state) to 4 (pronounced lymphodepletion). Gray matter injury (GMI) and white matter injury (WMI) were classified as older, recent, or absent, and ATI was correlated with GMI, WMI, thymic weight, and clinical data. Nine cases (16%) had ATI grade 0-1; 19 (33%), grade 2; 24 (41%), grade 3; and 6 (10%), grade 4. Older GMI and WMI were present in 39 (67%) and 10 (17%) stillborns, respectively. Higher ATI grade correlated significantly with older GMI (P < 0.001) and WMI (P  =  0.014). The ATI grade was higher in the small-for-gestational stillborns compared with the appropriate- or large-for-gestational stillborns (P  =  0.017) but did not correlate significantly with gestational age or other clinical or demographic factors evaluated. The ATI grades 2-4 were found in 84% of the stillborns, consistent with onset of acute illness between 24 and >72 hours before demise. Higher ATI grade correlated significantly with older brain injury, suggesting similar time of onset and shared underlying pathophysiologic events, the specific nature of which remains unclear.

The neuropathology of stillbirth - correlation with apolipoprotein genotype in a Scottish population based study

BACKGROUND

The neuropathology of stillbirths has been widely studied but rarely on a population basis. Whether foetal apolipoprotein E (APOE) genotype exerts any influence has been little investigated, despite well known effects in adult brains.

AIMS

To establish the neuropathology of a population cohort of stillbirths and compare with the APOE genotype.

STUDY DESIGN AND SUBJECTS

The brains of 191 stillbirths (≥24weeks of gestation) were recruited from a Scottish population cohort and grouped by clinical history. APOE genotype was available for 97%.

RESULTS AND CONCLUSIONS

One or more neuropathological features, most appearing relatively recent, were found in 54% of 157 antepartum singletons, 44% of 9 abruption-associated stillbirths, 85% of 13 in multiple pregnancies but in only 19% of 12 intrapartum stillbirths. White matter injury (WMI) occurred in 36% of preterm and 21% mature stillbirths. Fresh petechial haemorrhages were common in all groups (29%) but germinal matrix haemorrhage (GMH) (7%) and periventricular leucomalacia (1%) were confined to preterm. GMH was significantly associated with WMI (p=0.003). Placental inflammation was common in intrapartum stillbirths (50%), compared with antepartum (15%), multiple pregnancy (23%) and abruption (0%). β-Amyloid precursor protein (βAPP) positive axons (36% stillbirths overall) correlated closely with WMI (p<0.0001), justifying future routine inclusion in foetal neuropathological investigation. This study highlights the paucity of brain damage in intrapartum stillbirths. While APOE2 was significantly overrepresented in stillbirths, there was no correlation between APOE genotype and neuropathological findings. We conclude that APOE does not influence neuropathological outcomes in stillbirths.

Antenatal brain injury in third trimester neonates with severe congenital anomalies: an autopsy study

OBJECTIVE

With advances in therapy, more neonates with severe congenital anomalies are surviving, albeit some with neurologic disorders, possibly related to antenatal low brain blood flow. This autopsy series reports antenatal brain injury in neonates expiring due to severe anomalies, and provides correlation with umbilical cord blood gas and acid-base analysis.

METHODS

We identified autopsies of third trimester neonates expiring shortly following delivery due to severe anomalies or malformations. Brain injury classified as "older" included periventricular leukomalacia, gliosis and karyorrhectic neurons, and "recent" included red neurons and reactive glial changes.

RESULTS

We identified 22 cases (nine term, 13 preterm). 16 (73%) had brain injury, including 11 with older injury. Cord arterial blood was analyzed in 17, and six had pH <7 or base deficit >12 mmol/L. Four out of 5 (80%) neonates with neuronal necrosis compared to two out of 12 (17%) without had a pH <7 or base deficit >12 mmol/L (p = 0.03). Five out of nine (56%) neonates with white matter injury compared to one out of 8 (13%) without had pH <7 or base deficit >12 mmol/L (p = NS).

CONCLUSIONS

Antenatal brain injury is frequent in neonates with severe congenital anomalies. Severely abnormal cord blood analysis results correlate significantly with neuronal necrosis and show a trend toward white matter injury; however, the absence of these abnormal results does not preclude the presence of brain injury.

Third trimester fetal demise occurring at time of delivery: correlation of autopsy findings and placental pathology with emphasis on antenatal central nervous system injury

OBJECTIVE

Third trimester fetal deaths occurring in the hospital at the time of delivery are unusual. We report an autopsy series of such cases with emphasis on neuropathological injury and other lesions predating delivery.

METHODS

We identified autopsies performed on third trimester fetuses documented to be alive shortly before delivery, but that expired during, or very close to, time of delivery, and we correlate autopsy and placental findings. Fetuses with major congenital anomalies were excluded.

RESULTS

Ten cases were identified (6 term, 4 preterm). All were delivered by cesarean section and had attempted resuscitation. Established or recent brain injury was identified in 9 of 10 cases, including 3 with established neuronal damage and 1 with periventricular leukomalacia. Additional autopsy findings included thymic involution in eight (five mild; three severe), myocardial infarcts in two; intrathoracic petechiae in five, and ascites or pleural or pericardial effusions in six. Severe thymic involution and myocardial infarcts correlated with established brain injury. Placental lesions adaptive to decreased oxygenation (increased nucleated red blood cells or villous hypervascularity) were seen in five cases and correlated with established brain injury. Acute chorioamnionitis with funisitis was present in one, and chronic inflammatory placental lesions were present in six.

CONCLUSIONS

These findings indicate brain injury predated the time period immediately before delivery in 9 of 10 fetuses, and in the fetuses with established brain injury the onset of acute illness was possibly >72 h before delivery.

Correlation of Placental Pathology with Perinatal Brain Injury

The purpose of placental pathology is to explain adverse clinical outcomes. One of the most tragic of these outcomes is perinatal brain injury with subsequent neurodisability. Findings in the placenta can play an important role in documenting sentinel events, uncovering clinically silent thromboinflammatory disease processes, revealing developmental alterations in functional reserve, and suggesting alterations in related maternal and fetal physiology. These findings, when integrated with clinical data, provide a plausible explanation for an otherwise unexpected outcome and can be helpful for treating physicians and family members.

Fetal central nervous system injury in third trimester stillbirth: a clinicopathologic study of 63 cases

We report the neuropathologic findings and clinicopathologic associations in 63 3rd trimester singleton stillborn fetuses. All were ≥ 28 weeks estimated gestational age (EGA) with complete autopsies, including placental examination. Fetuses with chromosomal abnormalities, major congenital anomalies, and intrapartum demise were excluded. The cases were divided into those with abruption (n  =  12) and those with unexplained fetal demise (n  =  51). The latter group was then subdivided by gestational age with 3 subgroups (preterm 28 to < 32 weeks EGA (n  =  16), preterm 32 to <37 weeks EGA (n  =  13), and term 37-41 weeks EGA (n  =  22). Each group was further subdivided as appropriate-for-gestational age/large-for-gestational age (AGA/LGA) or small-for-gestational age (SGA). Placental lesions were also evaluated and correlated with brain lesions. Established or recent injury involving gray or white matter was seen in 88% of the fetuses with unexplained demise versus 42% with abruption (P  =  0.001). The most common form of brain injury was established gray matter damage, seen in 65% of the fetuses with unexplained demise versus 25% with abruption (P  =  0.021), the most common pattern being established pontosubicular neuronal necrosis plus established neuronal necrosis in other sites. There was no significant difference in the frequency of brain injury between the SGA fetuses and AGA/LGA fetuses or between the unexplained stillbirth preterm and term subgroups, and there was no unequivocal correlation between placental lesions and brain lesions. Brain injury, most frequently established gray matter damage, is seen in the majority of stillborn infants with unexplained demise, indicating that the brain injury predates the period immediately before death.

Third-trimester stillbirths: correlative neuropathology and placental pathology

Although in recent years placental pathology has been the subject of a wealth of detailed descriptions and diagnostic categorization, systematic correlation of these conditions with the pathology of stillbirth has not been attempted. We examine the relationship between specific inflammatory, maternal, and fetal vascular pathologies and the central nervous system pathology and histological indicators of fetal compromise. Our design was a retrospective case series of 37 3rd-trimester intrauterine fetal deaths. In general, mixed placental pathologies were the rule, with three quarters of the placentas demonstrating combinations of maternal vascular pathology, fetal vascular pathologies, umbilical cord abnormalities, or inflammatory lesions. The range of brain pathology was limited to acute, severe congestion, white matter edema, and neuronal karyorrhexis (pontosubicular necrosis with or without neuronal karyorrhexis at other sites). Established periventricular leukomalacia was present in only 2 cases. The presence of neuronal karyorrhexis or white matter gliosis was correlated with the presence of a high-grade inflammatory lesion and with fetal thymic involution. Neuronal karyorrhexis, but not white matter gliosis, correlated as well with histologically established fetal vascular lesions in the placenta, even once the effect of inflammation was accounted for. Gliosis also correlated with inflammation, meconium staining, and thymic involution. Central nervous system injury may be the end result of complex placental pathologies, and neuronal injury may be a consequence of the fetal inflammatory response. The correspondence between the time courses of histological features of chorioamnionitis, neuronal karyorrhexis, and thymic involution points to irreversible central nervous system injury being common 12-48 hours prior to in utero demise.

The black box of perinatal ischemic stroke pathogenesis

An improved understanding of perinatal stroke epidemiology, classification, neuroimaging, and outcomes has emerged in recent years. Despite this, little is known regarding the pathophysiological mechanisms responsible for most cases. A multitude of possible associations and putative risk factors have been reported, but most lack definitive empirical evidence supporting primary causation. These include obstetrical and maternal factors, perinatal conditions, infectious diseases, prothrombotic abnormalities, cardiac disorders, medications, and many others. The bulk of evidence is weak, dominated by case reports and retrospective case series. Findings from the small number of case-control and cohort studies that exist are limited by heterogeneous populations and methodologies. The single largest barrier to ultimately understanding and potentially improving outcomes from this common and disabling condition is the lack of comprehensive, fully powered risk factor studies required to definitively describe perinatal stroke pathogenesis. This review summarizes current evidence and suggests future directions for research.

[Cerebral palsy and perinatal asphyxia (II--Medicolegal implications and prevention)]

Obstetric litigation is a growing problem in developed countries and its escalating cost together with increasing medical insurance premiums is a major concern for maternity service providers, leading to obstetric practice cessation by many practitioners. Fifty-four to 74 % of claims are based on cardiotocographic (CTG) abnormalities and their interpretation followed by inappropriate or delayed reactions. A critical analysis is performed about the nine criteria identified by the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics in their task force on Neonatal Encephalopathy and Cerebral Palsy: four essential criteria defining neonatal asphyxia and five other suggesting an acute intrapartum event sufficient to cause cerebral palsy in term newborns. The importance of placental histologic examination is emphasized in order to confirm sudden catastrophic events occurring before or during labor or to detect occult thrombotic processes affecting the fetal circulation, patterns of decreased placenta reserve and adaptative responses to chronic hypoxia. It may also exclude intrapartum hypoxia by revealing some histologic patterns typical of acute chorioamnionitis and fetal inflammatory response or compatible with metabolic diseases. Magnetic resonance imaging (MRI) of the infant's damaged brain is very contributive to elucidate the mechanism and timing of asphyxia in conjunction with the clinical picture, by locating cerebral injuries predominantly in white or grey matter. Intrapartum asphyxia is sometimes preventable by delivering weak fetuses by cesarean sections before birth, by avoiding some "sentinel" events, and essentially by responding appropriately to CTG anomalies and performing an efficient neonatal resuscitation. During litigation procedures, it is necessary to have access to a readable CTG, a well-documented partogram, a complete analysis of umbilical cord gases, a placental pathology and an extensive clinical work-up of the newborn infant including cerebral MRI. Malpractice litigation in obstetric care can be reduced by permanent CTG education, respect of national CTG guidelines, use of adjuncts such as fetal blood sampling for pH or lactates, regular review of adverse events in Clinical Risk Management (CRM) groups and periodic audits about low arterial cord pH in newborns, admission to neonatal unit, the need for assisted ventilation and the decision-to-delivery interval for emergency operative deliveries. Considering the fast occurrence of fetal cerebral hypoxic injuries, and thus despite an adequate management, many intrapartum asphyxias will not be preventable. Conversely, well-documented hypoxic-ischemic brain insults during the antenatal period do not automatically exclude intrapartum suboptimal obstetric care.

Neonatal arterial ischaemic stroke: obstetric issues

Perinatal arterial ischaemic stroke (PAIS) is increasingly recognised as an important cause of neurological morbidity in children. The aetiology remains unclear although perinatal risk factors have been identified from limited case series. Risk factors for PAIS in term infants are different from those in preterm infants. Maternal primiparity, infertility, cocaine use, prothrombotic disorders, prolonged rupture of membranes, abnormal cardiotocograph, instrumental deliveries and emergency caesarean sections are reported risk factors in term infants. Uncomplicated vaginal delivery and prelabour caesarean section are uncommon in cases of PAIS. The presence of multiple risk factors increases the odds of developing PAIS. For preterm babies, fetal heart abnormalities, twin-twin transfusion and hypoglycaemia are recognised risk factors. Larger cohort studies are required to elucidate further the multifactorial pathway to perinatal arterial stroke.

Disorders of placental circulation and the fetal brain

Disorders of the placental circulation, including the release of deleterious mediators to the fetus, are important risk factors for central nervous system complications. These disorders result in discrete patterns of placental injury detectable by a thorough placental pathologic examination. Consideration of the location, severity, multiplicity, and timing of these lesions is critical to a full understanding of their significance. Less than 10% of placentas from term infants that later develop cerebral palsy lack any evidence of placental abnormalities potentially related to adverse outcome.

The placenta as witness

The placenta not only "records" and reflects the intrauterine environment, it also provides valuable information on the cause and timing of many adverse events and conditions. The placenta may be useful in several ways. It may be the cause of injury due to an inherent abnormality, it may "malfunction" because of disease processes that are not primarily placental in origin, or it may merely reflect an abnormal intrauterine environment. Not only may the etiology of the injury be ascertained from placental examination, but also a time frame during which the abnormal condition has been operating. Acute lesions may be associated with sudden catastrophic events, whereas other, more chronic lesions lead to decreased placental reserves. Markedly depleted reserves will render the infant susceptible to other, sometimes more acute, events and thus are also associated with significant injury or even death.

Placental lesions as predictors of cerebral palsy and abnormal neurocognitive function at school age in extremely low birth weight infants (<1 kg)

Extremely low birth weight (ELBW) infants (<1 kg) have high rates of neurodisability. Although previous studies have implicated placental lesions in adverse short-term neurologic outcomes in this population, none have assessed their effects in these children once they reach school age. We conducted a secondary analysis of placental pathology in a cohort study of inborn singleton ELBW infants born between 1992 and 1995 and evaluated for cerebral palsy (CP) and abnormal neurocognitive testing at 8 years of age (N = 129). The neurocognitive tests were the Kaufman Assessment Battery for Children (K-ABC) and 6 subtests of the NEPSY: A Developmental Neuropsychological Assessment. We found that placental lesions associated with maternal vascular underperfusion (increased syncytial knots and acute atherosis) were risk factors for CP, while villous edema was associated with low scores on both neurocognitive tests. Histologic chorioamnionitis (HCA) was not predictive of outcome in the population as a whole, but a severe fetal vascular response was associated with a lower NEPSY score in the subpopulation with HCA (N = 69). Placentas with increased syncytial knots, villous edema, and those with neither finding constituted nonoverlapping subgroups with distinct pathologic and perinatal characteristics. Among infants with villous edema (N = 25), those with neurologic impairment had lower gestational ages and more severe degrees of HCA. However, by logistic regression these other factors were not independent risk factors for abnormal neurocognitive testing, and only HCA with a severe fetal vascular response decreased the association of villous edema with low test scores for NEPSY, but not K-ABC.

Intrapartum stillbirths in hospital unrelated to uteroplacental vascular insufficiency

The aim of this study was to investigate the causes of intrapartum asphyxia and its relationship to placental abnormalities. Twenty intrapartum fetal death autopsies carried out over a 10-year period in one hospital pathology department associated with a large obstetric unit were reviewed. All the intrapartum fetal deaths occurred in the hospital, while the mothers were being monitored during and after labor. On morphologic grounds, all the fetal deaths were thought to be caused by intrapartum asphyxia. Seven of the intrapartum fetal deaths were associated with intrauterine infection causing funisitis, and in 6 of these cases, chorioamnionitis was present as well. Two cases were caused by placental abruption, and 1 case was caused by cord compression. In 8 of the 10 remaining cases in which the placenta was examined, a minor placental abnormality was detected in only 1 case. Five of the 10 cases had a mild astrocytosis in the intracerebral periventricular white matter, suggestive of intrauterine ischemia at least 12 hours before death. Five of the 10 cases were thought by the delivering obstetrician to have umbilical cord abnormalities. The main conclusions from this study are that, except in cases of intrauterine infection, placental vascular abnormalities are unlikely to be associated with intrapartum asphyxia leading to fetal death during labor. The number of cases with umbilical cord abnormalities raises the possibility that cord accidents may be a significant cause of intrapartum stillbirth.

My approach to performing a perinatal or neonatal autopsy

An opportunity to determine the cause of death, factors that may have a role in it, and the extent and cause of malformations is provided by perinatal autopsy. The family may be assisted in finding closure after the death of their infant by the information obtained. Insight into classifying infants appearing normal into one of three groups, small, appropriate and large for gestational age, has been provided, as each group tends to have specific causes of death. In infants with congenital anomalies, patterns of malformation may lead us to the diagnosis. An accurate diagnosis is required to provide counselling for a subsequent pregnancy.

Stroke in the fetus and neonate

Multiple patterns of focal ischemic injury in the fetal and perinatal brain are now recognized as important causes of neurological disability in children. Strokes may be arterial or venous, symptomatic or subclinical, and can occur across multiple timeframes. Establishing the importance of an increasing number of potential risk factors and translating that knowledge into an improved understanding of pathophysiology are major challenges. Advanced neuroimaging has facilitated increased recognition of perinatal stroke and an improved understanding of plasticity mechanisms in the developing brain. Better outcome prediction will assist in patient selection for advancing neuroprotective strategies to reduce cerebral palsy and other adverse outcomes suffered by most children.

Placental pathology and cerebral palsy

Recent classification systems of cerebral palsy call for an assessment of the timing and etiology of brain injury. The placenta is an underused resource for addressing these important questions. An expert assessment of the placental pathology can provide temporally and mechanistically specific data not available from any other source. Key concepts for an understanding of the role of placental pathology are the "sentinel lesion," the high prevalence of thromboinflammatory lesions affecting large fetal placental vessels, the significance of underlying placental reserve, and the realization that placental findings can serve as markers for processes occurring in the mother or fetus.

Cerebral palsy secondary to perinatal ischemic stroke

Congenital hemiplegia is the most common form of cerebral palsy in children born at term, and stroke is the number one cause. Neonatal ischemic stroke includes perinatal arterial ischemic stroke, presumed pre- or perinatal stroke, and cerebral sinovenous thrombosis, all of which have emerged as important contributors to cerebral palsy. Of increasing interest is how the overlapping list of associations and risks for stroke and cerebral palsy relate to each other. Stroke-induced injury is focal, and the preservation of normal areas of brain may afford unique opportunities for plastic adaptation. The implications of this essential difference are stressed in a discussion of how the epidemiology, pathophysiology, diagnosis, and therapeutic advancements in perinatal stroke relate to the outcome of cerebral palsy.

Laminar necrosis of placental membranes: a histologic sign of uteroplacental hypoxia

Laminar necrosis of placental membranes (LN), a band of coagulative necrosis at the choriodecidual interphase, is a histologic lesion of unclear pathogenesis that has been reported in placentas from preeclampsia, preterm premature rupture of membranes, and preterm abruption. To better explore other possible correlations of LN, we performed a retrospective case-control study in which data on pregnancy risks and outcomes, neonate conditions, and placental gross, routine microscopic, and selected immunohistochemistry examinations in 52 consecutive cases of LN were compared with 52 gestational age-matched control cases without LN. Maternal hypertensive disorders and combinations of 2 or more maternal, fetal, neonatal, or placental conditions known to be potentially associated with uteroplacental hypoxia were more prevalent in patients with LN than in control patients. By immunohistochemistry, LN areas were positive for complement 9 (marker of necrosis) and negative for active caspase 3 (marker of irreversible apoptosis), nitrotyrosine residues (marker of oxidative stress), and Ki-67 (proliferation marker), thus confirming their necrotic rather than apoptotic nature. However, LN areas were flanked by caspase 3 positivity, and the positivity for nitrotyrosine residues was more pronounced in the decidua and mesenchyme in the same membrane rolls as LN, which indicates a probable role of apoptosis and oxidative stress in the development of LN. Based on these immunohistochemical results and clinicopathologic correlations, we believe LN should be recognized and reported as a hypoxic placental lesion.

Determining the contribution of asphyxia to brain damage in the neonate

Studies in the research laboratory have demonstrated the complex relationship between fetal and newborn asphyxia and brain damage, a balance between the degree, duration and nature of the asphyxia and the quality of the cardiovascular compensatory response. Clinical studies would support the contention that the human fetus and newborn behave in a similar manner. An accurate diagnosis of asphyxia requires a blood gas and acid base assessment. The clinical classification of fetal asphyxia is based on a measure of metabolic acidosis to confirm that fetal asphyxia has occurred and the expression of neonatal encephalopathy and other organ system complications to express the severity of the asphyxia. The prevalence of fetal asphyxia at delivery is at term, 25 per 1000 live births of whom 15% are moderate or severe; and in the preterm, 73 per 1000 live births of whom 50% are moderate or severe. It remains to be determined how often the asphyxia recognized at delivery may have been present before the onset of labor. There is a growing body of indirect and direct evidence to support the contention that antepartum fetal asphyxia is important in the occurrence of brain damage. Although much of the brain damage observed in the newborn reflects events that occurred before delivery, newborn asphyxia and hypotension, particularly in the preterm newborn, may contribute to the brain damage accounting for deficits in surviving children.

Placental vascular compromise in jejunoileal atresia

BACKGROUND/PURPOSE

The mechanisms of intrauterine vascular disruptions that result in the development of jejunoileal atresia (JIA) are not fully understood. Monochorionic twinning with fetal death of a cotwin is known to be correlated with the development of JIA in the survivor through placental communication. The aim of this study was to evaluate whether other placental vascular compromises might contribute to the development of JIA.

METHODS

Forty-five newborns (23 boys and 22 girls) who were treated for JIA at Tsukuba University Hospital from 1978 to 2003 were reviewed. Placental findings were informative in 23 cases.

RESULTS

No or slight abnormality of the placenta was found in 19 cases. Significant placental abnormalities were found in 4 patients who also had a low birth weight. One patient with apple peel atresia (APA) had excessive torsion of the umbilical cord (UC), which was inserted at the margin of the placenta, and there was an adjacent area of infarction. One patent with multiple atresia (MA) was a surviving monochorionic twin with intrauterine fetal death of the other. Another case of MA showed marginal insertion of the UC. Severe placental abnormalities including wide infarction, cyst formation, and marginal insertion of the UC were found in 1 case of MA. These 3 cases of MA were complicated with other anomalies including brain anomaly.

CONCLUSIONS

Placental vascular compromises were involved infrequently in JIA but might possibly be responsible for the development of JIA as well as associated anomalies and a low birth weight as chronic insults since an early stage of gestation in some cases.

The value of autopsy in determining the cause of failure to respond to resuscitation at birth

Autopsy is invaluable in identifying the causes of severe depression and very low Apgar score after birth and in assessing contributory conditions. Brain scans are increasingly used in the care of neonates who fail to respond to resuscitation at birth but their interpretation depends on the information gained from sound neuropathological studies. Asphyxia, both acute intrapartum asphyxia and chronic asphyxia, is an important cause of low Apgar scores. The gestational age and the nature of the asphyxial insult both have a profound influence on the ultimate pattern of injury. Asphyxia in the preterm brain tends to damage preferentially the white matter but some white matter damage is also seen in many infants who have an hypoxia-ischaemic insult at term though the predominant site of injury is to the central grey matter. The nature of the cellular damage and reactive change seen at autopsy is described. There is an association between low Apgar scores and intrauterine exposure to infection and maternal pyrexia. Detailed autopsy examination should include the search for infection. The placenta, cord and membranes should be examined in view of the mounting evidence of the association between intrauterine infection of the placenta and fetal membranes and prenatal brain damage. Additionally, the presence of placental thrombosis and infarction should be sought in relation to focal and global injury in the full term infant. Acquired prepartum lesions rarely cause the infant to present with a low Apgar score. The exception to this is severe damage to the brainstem and basal ganglia. Traumatic injury to the brain is now much less common than in previous decades. Subdural haemorrhage occurs more frequently than intraventricular or subarachnoid haemorrhage. Instrumental and assisted deliveries are associated with an increased incidence of subdural haemorrhage though these rarely cause significant long term damage. Careful autopsy, particularly of the neck and paravertebral tissues, spinal cord, brainstem and nerve roots is important where trauma is suspected. Tearing of nerve roots or fibre bundles in the spinal cord is readily demonstrated under the microscope using immunocytochemistry to beta-amyloid precursor protein. Disorders of the spinal cord, peripheral nerve and muscle as well as some metabolic diseases may cause a baby to be both floppy and weak. Metabolic disease, including peroxisomal disorders, non-ketotic hyperglycinaemia, lipid and glycogen storage disorders and mitochondrial diseases may cause profound hypotonia and respiratory failure at birth or shortly afterwards.

Neonatal arterial ischemic stroke and cerebral sinovenous thrombosis are more commonly diagnosed in boys

The risk factors for arterial ischemic stroke and cerebral sinovenous thrombosis in neonates are not well understood. We looked at gender, birthweight, and gestational age in neonates with arterial ischemic stroke and cerebral sinovenous thrombosis to see if there were trends suggesting that these were risk factors. We identified neonates with a gestational age at birth > or = 36 weeks and a diagnosis of arterial ischemic stroke or cerebral sinovenous thrombosis made by computed tomography or magnetic resonance imaging during the neonatal period from a consecutive cohort study of children with arterial ischemic stroke and cerebral sinovenous thrombosis in Ontario. Data on gender, birthweight, and gestational age were obtained by health record review. Sixty-six children with neonatal arterial ischemic stroke were identified. Forty-one (62.1%; 95% CI 49.3-73.8%) were male. Thirty-two children with neonatal cerebral sinovenous thrombosis were identified. Twenty-five (78.1%; 95% CI 60.0-90.7%) were male. One male child was identified with both arterial ischemic stroke and cerebral sinovenous thrombosis. There was a trend toward higher than average birthweights among neonates with arterial ischemic stroke and a trend toward older gestational age in female neonates with arterial ischemic stroke. Our data suggest that neonatal arterial ischemic stroke and cerebral sinovenous thrombosis are more commonly diagnosed in boys. The slightly larger size of male neonates may be contributory in arterial ischemic stroke. It is not known whether boys are at higher risk of developing arterial ischemic stroke and cerebral sinovenous thrombosis or are simply more likely to present with symptoms resulting in diagnosis. These issues need further study.

Reflections on the occurrence and significance of antepartum fetal asphyxia

This chapter documents the growing evidence of the occurrence and significance of antepartum fetal asphyxia. Perinatal mortality studies demonstrate that the majority of fetal deaths, including those due to asphyxia, occur in the antepartum period. Epidemiological studies of cerebral palsy conclude that a minority of cases of cerebral palsy are due to intrapartum fetal asphyxia and implicate antenatal events, including asphyxia. Cordocentesis studies have confirmed that antepartum fetal asphyxia occurs in the growth-restricted fetus and might contribute to the increase of stillbirths and cerebral palsy in these children. Blood gas and acid-base studies in the immature fetus have demonstrated the increased prevalence of fetal asphyxia, and particularly of moderate or severe asphyxia, of which the majority might occur in the antepartum period. The ultimate determination of the prevalence and significance of antepartum fetal asphyxia requires the development of a non-invasive specific measure of fetal asphyxia.

Stroke in newborn infants

The few days before and after birth are a time of special risk for stroke in both mother and infant, probably related to activation of coagulation mechanisms in this critical period. Arterial ischaemic stroke around the time of birth is recognised in about one in 4000 full-term infants, and may present with neurological and systemic signs in the newborn. Neonatal seizures are most commonly the clinical finding that triggers assessment. In other children, perinatal stroke is recognised only retrospectively, with emerging hemiparesis or seizures after the early months of life. Risk factors for perinatal stroke include hereditary or acquired thrombophilias and environmental factors. Perinatal stroke underlies an important share of congenital hemiplegic cerebral palsy, and probably some spastic quadriplegic cerebral palsy and seizure disorders. There is much to be learned about the natural history of perinatal stroke, and there are as yet no evidence-based strategies for prevention or treatment.

Etiology of cerebral palsy

Cerebral palsy has a complex and multifactorial etiology. Approximately 5%-10% of cases can be ascribed to perinatal hypoxia, but the vast majority of cases are caused by the interplay of several risk factors and antenatal, perinatal, and neonatal events. The strongest risk factors include prematurity and low birth weight. The prevalence of cerebral palsy has remained constant despite improvements in obstetric and neonatal care. For a long time, the only causal factors explored to account for risk for cerebral palsy were complications of labor and delivery. As other periods have been investigated, new associations have come to light. The current understanding of contributors to the risk for cerebral palsy is still incomplete. Multiple causes may interact by way of excitotoxic, oxidative, or other converging pathophysiologic pathways. A single factor, unless present to an overwhelming degree, often may be insufficient to produce cerebral damage, whereas two or three interacting pathogenic assaults may overwhelm natural defenses and produce irreversible brain injury. The low prevalence of cerebral palsy makes the formal testing of preventative strategies difficult. There is a need for such strategies to be carefully assessed in well designed, multicenter, randomized, controlled trials before becoming part of clinical practice, however, so that the balance between harm and benefit is known in advance.

The effects of repeated endotoxin exposure on placental structure in sheep

Intrauterine infection has been associated with fetal brain injury and preterm birth. We have recently shown that repeated exposure to bacterial endotoxin leads to hypoxia and brain injury in the preterm ovine fetus and we considered it possible that endotoxin could also damage the placenta. Our aim therefore was to assess placental structure following repeated exposure to endotoxin. Endotoxin was administered on 3-5 occasions (1 microg/kg, i.v.) over 5 days from 95-99 days of gestation (term approximately 147 days) to 6 fetal sheep and placental structure assessed at 105 days. In LPS-exposed animals there was a 17 per cent reduction (P<0.05) in placental weight and the average cross-sectional area of placentomes was reduced (P<0.05) by 20 per cent. In addition, all LPS-exposed placentae showed significant injury as evidenced by calcium deposits associated with areas of infarcted tissue. We conclude that repeated endotoxin exposure results in damage to the placenta which could lead to persistent alterations in placental exchange function.

Antepartum fetal asphyxia in the preterm pregnancy

OBJECTIVE

The objective of this report was to provide insight into the frequency and characteristics of antepartum fetal asphyxia in pregnancies that are delivered preterm.

STUDY DESIGN

The characteristics of 30 pregnancies that were delivered preterm with biochemically confirmed antepartum fetal asphyxia (umbilical artery base deficit of >12 mmol/L) that were derived from >1 decade of experience in a single tertiary care obstetric unit were examined. Antepartum clinical characteristics, fetal assessment tests, and neonatal complications were documented. Fetal asphyxia was classified as mild, moderate, or severe on the basis of an umbilical artery base deficit (>12 mmol/L) and newborn encephalopathy and other organ system complications.

RESULTS

Antepartum fetal asphyxia accounted for at least 34% of the fetal asphyxia in the pregnancies that were delivered preterm. Predictive criteria that led to intervention and diagnosis included clinical risk factors and, particularly, abnormal fetal assessment tests. The 50% incidence of moderate or severe asphyxia in the antepartum preterm pregnancies compares with 15% in term pregnancies. Moderate or severe asphyxia occurred with equal frequency with early and delayed intervention.

CONCLUSION

Fetal asphyxia in pregnancies that were delivered preterm is present frequently before the onset of labor. Abnormal fetal assessment tests are valuable predictors of antepartum fetal asphyxia. The increased frequency of moderate and severe fetal asphyxia in the pregnancy that is delivered preterm implies a greater likelihood of long-term morbidity or death.

Neuropathology associated with stillbirth

Neuropathologic findings in stillbirths oftentimes provide insight into the specific mechanisms leading to death. Examination of the brains of stillborn infants may also identify pathophysiologic processes that result in prenatal brain injury in liveborn as well as stillborn infants and that lead to neurologic disorders in liveborn infants, such as cerebral palsy or the sudden infant death syndrome (SIDS). A variety of abnormalities are found in the brains of stillborns, the most common including cerebral white matter necrosis (periventricular leukomalacia) or gliosis, germinal matrix or intraventricular hemorrhage, cerebral infarcts, pontosubicular necrosis, and spinal cord or brainstem necrosis. The 2 major hypotheses that have been proposed for the pathophysiology of cerebral white matter injury in the perinatal period are hypoxia/ischemia and infection/cytokines as the basis for injury. The fetal brain may be selectively vulnerable to various insults at specific stages of development.

Enteric glial cells. An upstream target for induction of necrotizing enterocolitis and Crohn's disease?

As a direct consequence of the sophisticated arrangement of its intrinsic neurons, the gastrointestinal tract is unique among peripheral organs, in its ability to mediate its own reflexes. Neurons of the enteric nervous system are intimately associated with enteric glial cells. These supporting cells do not resemble Schwann cells, the glial cell found in all other parts of the peripheral nervous system, but share many similarities with astrocytes of the central nervous system. Ablation of enteric glial cells in adult transgenic mice has demonstrated that these cells are essential to maintain the integrity of the small intestine. Acute loss of enteric glial cells induces massive pathological changes with similarities to necrotizing enterocolitis (NEC) and early Crohn's disease. These human conditions share some mechanistic similarities. Identification of enteric glial cell dysfunction/loss as sufficient to induce necrotic/inflammatory bowel disease may be important to understand the pathogenesis of both NEC and Crohn's disease.

Cerebrovascular disorders in children with the factor V Leiden mutation

Since 1995, at least 128 children with a cerebrovascular disorder, cerebral palsy, or both and the factor V Leiden mutation have been reported. The majority of these strokes were in the first year of life, many of them in the perinatal period. Two thirds had an additional exogenous risk factor for thrombosis, and 42% had another recognized endogenous prothrombotic risk factor in combination with the mutation. We review the association of the factor V Leiden mutation and a cerebrovascular disorder in children younger than 16 years of age and describe the clinical features of 8 children with cerebral palsy and the Leiden mutation. This mutation should be considered in the evaluation of children with a stroke or its sequelae, including infants with perinatal stroke.

Placental lesions associated with cerebral palsy and neurologic impairment following term birth

OBJECTIVE

The aim of this study was to determine the association of placental findings with cerebral palsy and related forms of neurologic impairment (NI) following birth at > or =37 weeks gestation (term).

DESIGN

In a retrospective comparison, placentas from 40 term infants with NI ascertained on the basis of clinicopathologic review for medicolegal consultation were compared with placentas from 176 consecutive meconium-stained term infants at low risk for NI.

RESULTS

After stratification for severity, 9 lesions were significantly increased in placentas from infants with NI: 5 lesions generally considered to occur within days of the time of labor and delivery (meconium-associated vascular necrosis, severe fetal chorioamnionitis, chorionic vessel thrombi, increased nucleated red blood cells, and findings consistent with abruptio placenta) and 4 lesions generally believed to have their onset long before labor and delivery (diffuse chronic villitis, extensive avascular villi, diffuse chorioamnionic hemosiderosis, and perivillous fibrin). Findings independently associated with NI by logistic regression in this descriptive study were severe fetal chorioamnionitis (odds ratio [OR], 13.2; 95% confidence interval [CI], 1.2-144); extensive avascular villi (OR, 9.0; 95% CI, 1.6-51); and diffuse chorioamnionic hemosiderosis (OR, 74.8; 95% CI, 6.3-894). The risk of NI increased as a function of the number of lesions present (OR, 10.1; 95% CI, 5.1-20 for each additional lesion), particularly when lesions generally considered to occur near the time of labor and those believed to occur well before labor were found in the same placenta (OR, 94.2; 95% CI, 11.9-747).

CONCLUSIONS

These findings suggest that placental pathology can contribute to an understanding of the mechanisms that contribute to NI at term.

Development of the placental villous tree and its consequences for fetal growth

Co-ordinated development of the fetal villous tree of the placenta is necessary for continued fetal growth and well-being. Before fetal viability, blood vessel development within the developing immature intermediate villi (IIV) is characterized by branching angiogenesis, such that the placenta expands to produce 10-16 generations of stem villi. Once fetal viability is attained, a developmental switch occurs to form large numbers of gas-exchanging terminal villi (TV) by non-branching angiogenesis in mature intermediate villi (MIV). Several growth factors, including vascular endothelial growth factor (VEGF), placenta growth factor (PlGF), angiopoietins, and angiostatins are produced within the villi and act locally, via their receptors, to control angiogenesis. Their relative contributions to placental vascular development are not fully understood at the present time. Severe early-onset intrauterine growth restriction (IUGR) is characterized by absent/reversed end-diastolic flow velocity (ARED) in the umbilical arteries, leading to fetal hypoxia, acidosis and a substantial rise in perinatal mortality and morbidity. The placentas from such cases show a deficit in peripheral villous development, which may be perpetuated by the effects of oxygen (delivered by maternal blood into the intervillous space) upon VEGF-directed angiogenesis, the so-called 'placental hyperoxia' theory of villous maldevelopment. Trophoblast apoptosis is a significant feature of early-onset IUGR and may explain poor flow-independent transfer of nutrients to the fetus. Finally, since transgenic mouse studies highlight the importance of trophoblast-derived transcription factors for placental villous (labyrinth) development, it is possible that the villous trophoblast controls the orderly development of the underlying mesoderm and blood vessels into the fetal villi.

Why is the placenta being ignored?

The relationship between the frequency of published recommended indications for placental pathological examination and the frequency of requests for such examination in a population-based study of term newborn encephalopathy was examined. Only 11.2% of placentas among 276 case infants and 0.7% of placentas among 564 term control infants were examined. Using the criteria set out in a consensus statement by the American College of Pathologists, all 276 cases fulfilled multiple maternal, fetal and placental indications for placental examination. Furthermore 43.3% of control infants fulfilled at least one criterion. Of the 25 case placentas that underwent pathological review, 16 were reported as having no diagnostic abnormality Six cases (24%) showed clinically important findings: four had evidence of infection, one had multiple chorangiomata and one had thrombosis and rupture of the umbilical vein. Of the three remaining placentas, one showed funisitis, one showed minor lymphohistiocytic villitis and one was from monochorionic twins. To our knowledge there are no agreed Australian guidelines for when a placenta should be submitted for pathological examination. We suggest that until guidelines based on properly designed studies are developed it may be appropriate to store all placentas for at least 72 hours. If the infant develops neurological symptoms or requires unexpected admission to a neonatal intensive care unit then placental examination may reveal important aetiological diagnostic and prognostic information.

The relationship between placental and other perinatal risk factors for neurologic impairment in very low birth weight children

Placental abnormalities reflect antenatal disease processes that may interact with other perinatal risk factors to affect long-term outcome. We performed a nested case control analysis of placental and clinical risk factors associated with neurologic impairment (NI) at 20-mo corrected age (60 cases and 59 controls) using data collected in a prospective study of very low birth weight (less than 1500 g) infants born between 1983 and 1991. In a preliminary analysis we explored the relationship between clinical infection and histologic chorioamnionitis (CA). Only histologic CA with a fetal vascular response correlated with either clinical CA or early onset neonatal sepsis. We then assessed the relative contribution of the nine risk factors (four placental and five clinical) associated with NI at the univariate level by multiple logistic regression. Three risk factors were independent predictors of NI: severe cranial ultrasound abnormalities (odds ratio 13.6, 95% confidence intervals 4.5-66.7), multiple placental lesions (odds ratio 13.2, 95% confidence intervals 1.3-137.0), and oxygen dependence at 36 wk (odds ratio 4.2, 95% confidence intervals 1.2-14.6). Finally, a series of logistic regressions was conducted with the dependent variable changing as we moved back along the causal chain to explore the relationships between risk factors operating at different stages. This analysis suggested that antenatal variables that were not independent predictors of NI by multiple logistic regression exerted their effects through the following intermediate pathways: fetal grade 3 histologic CA via chorionic vessel thrombi, clinical CA via grade 3 villous edema, and grade 3 villous edema via severe cranial ultrasound abnormalities.

Physiologic basis of antenatal testing

Hypoxic injury accounts for approximately 20 to 40% of stillbirths in published autopsy series. Antepartum fetal testing modalities can discriminate between the fetus at risk for hypoxic injury and the normally oxygenated fetus. These modalities have resulted in a significant reduction in this category of stillbirths. The physiologic underpinning for the antepartum testing is reviewed with a brief discussion of the two major approaches to testing.

Intrapartum Fetal Surveillance. Is It Worthwhile?

Potentially significant intrapartum fetal asphyxia occurs in approximately 20 per 1000 births. Moderate and severe fetal asphyxia exposure with newborn morbidity occurs in 3 to 4 1000 births, with brain damage and subsequent disability in at least 1 per 1000 births. Although the prevalence of moderate and severe asphyxia is modest, prevention is important because of the serious implications of this complication to the child, family, and society. Because of the limited predictive value of clinical risk factors, the interpretation of patterns in a fetal heart rate record has become the primary screening test for intrapartum fetal asphyxia. Despite extensive clinic experience and numerous clinical trials, the benefits of EFM as a screening test have not been established, and harm may occur owing to unnecessary intervention. This observation raises serious ethical issues. When an intervention is initiated by the clinician rather than the patient, the clinician under greater obligation to ensure that the benefits outweigh the harm. Several factors complicate the demonstration of benefits of EFM as a screening test. There is no consensus regarding a protocol of fetal surveillance for low-risk patient who account for approximately 25% of intrapartum fetal asphyxia. Moderate and severe asphyxia cannot be prevented when asphyxial exposure has occurred before labor or before the onset of fetal surveillance. Prediction of intrapartum fetal asphyxia cannot occur when the quality of the record does not permit interpretation. Interpretation of predictive fetal heart rate patterns cannot occur unless the record is consistently and carefully scored. Prediction of most cases of intrapartum fetal asphyxia on the basis of fetal heart rate patterns is possible but difficult. Because the goal of intrapartum fetal surveillance is the prevention of moderate and severe fetal asphyxia, prediction must be achieved before fetal decompensation. Prediction must occur before absent baseline fetal heart rate variability evident in the record, which is uniformly associated with cerebral dysfunction and, in some cases, brain damage. The possibility of fetal asphyxia must be considered when, within a 1-hour window of recording, there are two or more cycles of minimal baseline fetal heart rate variability and two or more cycles of late or prolonged decelerations or both. Because approximately 9 of 10 predictive fetal heart rate patterns are false-positive, supplementary tests to confirm the diagnosis and to identify false-positives to prevent unnecessary intervention are essential. Until such time as additional fetal assessment tests are validated, blood gas and acid-base assessment of fetal blood can provide a definitive diagnosis and identify false-positive predictions.

Basilar artery occlusion and the dense artery sign in the newborn

A child with basilar artery occlusion in the neonatal period is reported. The occlusion was documented by unenhanced computed tomography performed in the neonatal period demonstrating a "dense" artery at the tip of the basilar artery. The pattern of cerebral damage on MRI scan at 10 years of age confirmed the site of the vascular occlusion. The evidence suggests that embolization was the operating pathogenic mechanism of cerebral vascular occlusion. Neonatal arterial thrombosis involving the carotid circulation has been well documented and may be due to many pathological factors including direct trauma to the carotid artery and embolization from remote sites. Thrombosis of the vertebral artery in the neonate is only rarely reported and only in association with significant cervical trauma. A second child with a similar pattern of cerebral injury demonstrated on neuroimaging is described suggesting that this event may be more common than recognized. The clinical features of basilar artery occlusion as seen in the adult are not apparent in the neonate. Recognition of the neuroimaging characteristics seen in this condition may help to provide the clinician with a reasonable pathogenetic explanation for unexplained cerebral injury.

[Periventricular leukomalacia. I. Histological and pathophysiological aspects]

The term 'periventricular leukomalacia' (PVL) usually covers necrotic and/or gliotic lesions from perinatal origin occurring in the periventricular ring of telencephalic white matter. PVLs are found post-mortem in one third of brains from autopsies of premature infants; PVLs are diagnosed in 4 to 10% of infants born before 33 weeks of gestation and remaining alive more than 3 days after birth. PVL is very rare in at term infants. The proportion of PVLs from prenatal origin is estimated between one third and one half of cases. Recent progresses in neuroepidemiology, developmental neurobiology and imaging methods permit to revisit the pathophysiology of PVLs on a multifactorial basis. The final result of these multiple factors seem to be calcium influx due to glutamatergic overactivation triggered by cytokines, infection and inflammation, and deficit in neurotrophic factors. Periventricular topography can be explained by properties of intracerebral vascular wall at this stage of angiogenesis and by perfusion failure/hypoxia.