Obstetric malpractice litigation: the pathologist's view

Classification of major newborn birth injuries

A classification system of various forms of major newborn birth injuries is clearly lacking in the literature. Currently, no scales exist for distinguishing degrees, extent, or distinctions of major birth injuries. The purpose of this study was to use published and online literature to explore the timing, prediction, and outcomes of major newborn birth injuries. Potential antecedents and causes were used in depicting what were reported to be major birth injuries. The outcome of this literature search was the development of a classification table synthesizing the most frequently reported (n = 20) major newborn birth injuries. This classification was developed according to (1) types of tissue involved in the primary injury, (2) how and when the injury occurred, and (3) the relationship of the injury to birth outcomes. A classification scheme is critically needed as the first step to achieving preventive interventions and plans for long-term recovery from birth injuries. Because major birth trauma contributes to increased neonatal morbidity and mortality, its occurrence requires careful study and preventive efforts to better promote newborn health.

A model of cerebral palsy from fetal hypoxia-ischemia

Disorders of the maternal-placental-fetal unit often results in fetal brain injury, which in turn results in one of the highest burdens of disease, because of the lifelong consequences and cost to society. Investigating hypoxia-ischemia in the perinatal period requires the factoring of timing of the insult, determination of end-points, taking into account the innate development, plasticity, and enhanced recovery. Prenatal hypoxia-ischemia is believed to account for a majority of cerebral palsy cases. We have modeled sustained and repetitive hypoxia-ischemia in the pregnant rabbit in utero to mimic the insults of abruptio placenta and labor, respectively. Rabbits have many advantages over other animal species; principally, their motor development is in the perinatal period, akin to humans. Sustained hypoxia-ischemia at 70% (E22) and 79% (E25) caused stillbirths and multiple deficits in the postnatal survivors. The deficits included impairment in multiple tests of spontaneous locomotion, reflex motor activity, motor responses to olfactory stimuli, and the coordination of suck and swallow. Hypertonia was observed in the E22 and E25 survivors and persisted for at least 11 days. Noninvasive imaging using MRI suggests that white matter injury in the internal capsule could explain some of the hypertonia. Further investigation is underway in other vulnerable regions such as the basal ganglia, thalamus and brain stem, and development of other noninvasive determinants of motor deficits. For the first time critical mechanistic pathways can be tested in a clinically relevant animal model of cerebral palsy.

High-risk obstetrics, medicolegal problems

The perinatal period is one of the most dangerous time of life. The responsibilities of the obstetricians are multifold. It is very difficult to draw a line between good and substandard care, therefore in perinatology and especially in high-risk obstetrical cases there are no absolute rules of management. The lay public is convinced through media channels, that modern reproductive research eliminated all the risks and hazards associated with childbirths, therefore only 100% healthy babies are accepted. Pregnancy is regarded as a 'success story' and if the baby is born with neurological defects (cerebral palsy) the parents and their advisors feel, that someone responsible for the defect should be found in the chain of management. This attitude starts a legal battle focusing on the events of labor and delivery. But in most cases it is very difficult to determine if a peripartal neonatal encephalopathy originated from the time period of labor and delivery, or started weeks earlier during pregnancy as an unnoticed event. Perinatal morbidity indicators are best based on neonatal clinical signs, which are predictive of later morbidity of the child. Neonatal seizures within 48 h of delivery of the baby could be a good index of later morbidity.

Umbilical cord blood acid-base state: what is normal?

OBJECTIVE

Umbilical cord blood gases and acid-base data from vigorous neonates were examined to determine normal values and ranges.

STUDY DESIGN

The University of California, San Francisco, Perinatal Data Base was used to retrieve information from deliveries between 1977 and 1993. Newborns with 5-minute Apgar scores > or = 7 were selected because it is generally accepted that a vigorous newborn has not had substantial intrapartum asphyxia lasting until delivery.

RESULTS

Full blood gas and obstetric data were available for 16,060 newborns. Of these, 15,073 (94%) had a 5-minute Apgar score > or = 7. The median umbilical artery values, with 2.5th percentile values in parenthesis, were pH 7.26 (7.10), PCO2 52 mm Hg (74), base excess -4 mEq x L(-1) (-11), and PO2 177 mm Hg (6). Although the distributions were skewed, the mean +/- 2 SDs were similar to these values. Data for these babies were further analyzed by method of delivery, gestational age, presentation, and presence of thick meconium. Although the means were significantly different in all groups, the differences between groups were relatively small.

CONCLUSION

A wide range of acid-base values were found in babies with normal Apgar scores, defining the "physiologic acidemia" of the normal vigorous newborn.

Neuropathology of the near-term and midgestation ovine fetal brain after sustained in utero hypoxemia

OBJECTIVE

The neuropathologic mechanisms of the ovine fetal brain in response to several hours of sustained hypoxemia with variable degrees of metabolic acidemia was investigated in both the preterm and near-term ovine fetus.

STUDY DESIGN

Three groups of fetuses were studied in each of the near-term and midgestation groups: a hypoxic group, a control group, and an uninstrumented control group. Histopathologic studies were performed after a 40-hour recovery period after experimentation.

RESULTS

Pathologic findings consisted of predominately white matter damage with some adjacent cortical necrosis but no selective neuronal injury. In the near-term group the hypoxia group fetuses demonstrated significantly higher white matter injury scores than did control group fetuses (p < 0.05). Periventricular white matter injury was the predominant pattern seen in the midgestation group.

CONCLUSIONS

In spite of normalization of biophysical and biochemical parameters after hypoxemia both midgestation and near-term fetuses sustained pathologic changes. Presence or extent of injury did not correlate with the degree of hypoxemia or metabolic acidosis achieved.

Does hypoxemia prevent brain damage in birth asphyxia?

The clinical syndrome of hypoxic ischemic encephalopathy (HIE) which occurs in association with birth asphyxia, is thought to represent a reperfusion injury consequent upon the generation of cytotoxic oxygen derived free radicals. It has recently been suggested that resuscitation of asphyxiated infants with unrestricted oxygen may aggravate the brain damage by causing hyperoxia and increased free radical production. To determine whether sustained hypoxemia may be protective in birth asphyxiated infants, we investigated the relationship between HIE and persistent pulmonary hypertension of the neonate (PPHN). The latter condition is also related to intrauterine and intrapartum birth asphyxia but is associated with persistent hypoxemia in the infant. In a retrospective analysis of 39 asphyxiated neonates admitted to the neonatal intensive care unit, we found that 28 had HIE, 10 had PPHN and only 1 had both HIE and PPHN. We therefore suggest that the hypoxemia due to PPHN may limit the production of oxygen derived free radicals in asphyxiated neonates and hence protect against the development of HIE. These findings lend support to current research into air vs. oxygen resuscitation for infants with birth asphyxia.

Diagnosis of birth asphyxia on the basis of fetal pH, Apgar score, and newborn cerebral dysfunction

Imprecise diagnosis of birth asphyxia coupled with uncertainties about causal factors for neurologic abnormalities in the newborn have greatly fueled the current litigation crisis in obstetrics. Our goal was to more precisely define birth asphyxia based on fetal condition as measured by umbilical artery blood pH, Apgar scores, and neurologic condition of newborns. We selected for study 2738 patients with singleton pregnancies with cephalic presentations who were delivered of infants at term to avoid complications such as prematurity, which may affect infant outcome independent of birth condition. The basis for study of these particular patients were defined criteria for high risk and an indicated arterial cord pH value. A total of five infants demonstrated cerebral dysfunction as evidenced by seizures during the neonatal period. Infection was linked to seizures in three of these infants; one infant had neonatal asphyxia and only one infant's clinical course could be attributed solely to birth events (uterine rupture). Stratification of umbilical artery blood pH values, Apgar scores, and combinations of these dependent variables in relation to newborn clinical outcomes revealed that infants must be severely depressed at delivery before birth asphyxia can be reliably diagnosed. Such depression includes Apgar scores less than or equal to 3 at 1 and 5 minutes plus umbilical artery pH values less than 7.00.