Commentary on the published position statement regarding the pathogenesis of fetal basal ganglia- thalamic hypoxic-ischaemic injury

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Late-onset fetal cardiac decelerations associated with fetal breathing movements

BACKGROUND

While late decelerations are regarded as signs of fetal hypoxemia, fetal breathing movements (FBM) associated with late decelerations invariably have normal outcomes. Could late decelerations sometimes represent FBM?

MATERIALS AND METHODS

Six patients between 37 and 42 weeks' gestation with 'late decelerations' associated with FBM (by ultrasound or tocodynamometer) during ante- or intrapartum monitoring were evaluated. Three were at high risk (diabetes, postdates, intrauterine growth restriction) and three were at low-risk.

RESULTS

'Late decelerations' arose in previously reassuring tracings. Oxygen or positional change had no effect. The decelerations were variable in length and shallow, and contained increased variability. Normal baseline rate and variability were maintained after the deceleration. Neonatal outcomes were normal.

CONCLUSION

'Late decelerations' as described are associated with normal outcome and may represent FBM. This understanding may reduce unnecessary interventions.

Medicolegal ramifications of electronic fetal monitoring during labor

Fetal heart rate patterns play a significant role in the modern day obstetric care. They also play a significant role in medicolegal allegations of negligence when the fetus suffers injury. Proper interpretation of the fetal monitor tracing is only one factor in the evaluation of the reasonableness of obstetric care. Appropriate care and optimal defense both derive from reasonable interpretation of pertinent clinical data, including the monitor strip, along with timely pursuit of a thoughtful, properly annotated, plan of care.

Intrapartum electronic fetal heart rate monitoring versus intermittent auscultation: a meta-analysis

OBJECTIVE

To use a meta-analysis of all published randomized trials to determine whether the use of continuous electronic fetal heart rate monitoring (EFM) as the main method of intrapartum fetal surveillance is associated with improved pregnancy outcome compared to intermittent auscultation.

DATA SOURCES

We used the MEDLINE data base and reference lists of articles to identify all published randomized trials of EFM versus intermittent auscultation.

METHODS OF STUDY SELECTION

A total of nine randomized trials published in peer-review journals were identified. The selection criterion was the use of EFM or intermittent auscultation as the main intrapartum fetal surveillance technique.

DATA EXTRACTION AND SYNTHESIS

A total of 18,561 patients were included in the nine published randomized trials, 9398 in the EFM group and 9163 in the auscultation group. Measures of pregnancy outcome included cesarean delivery, cesarean for suspected fetal distress, overall use of forceps or vacuum, use of forceps or vacuum for suspected fetal distress, overall perinatal mortality, and perinatal mortality due to fetal hypoxia (intrapartum or early neonatal death) attributable to the method of intrapartum monitoring. The meta-analysis showed that the patients monitored electronically had a significantly higher overall cesarean rate (odds ratio [OR] 1.53, 95% confidence interval [CI] 1.17-2.01), higher cesarean rate for fetal distress (OR 2.55, 95% CI 1.81-3.53), overall increased use of forceps or vacuum (OR 1.23, 95% CI 1.02-1.49), increased use of forceps or vacuum for suspected fetal distress (OR 2.50, 95% CI 1.97-3.18), and decreased perinatal mortality due to fetal hypoxia (OR 0.41, 95% CI 0.17-0.98).

CONCLUSION

Electronic fetal monitoring is associated with increased rates of surgical intervention and decreased perinatal mortality due to fetal hypoxia.

Intrapartum, atraumatic, non-asphyxial intracranial hemorrhage in a full-term infant

BACKGROUND

Intracranial hemorrhage in a full-term infant is uncommon, is usually subarachnoid in type, and is usually associated with operative vaginal delivery or asphyxia.

CASE

A 15-year-old primigravid woman at 37 weeks' gestation developed a prolonged second stage of labor associated with persistent occiput posterior position. With the onset of pushing, baseline fetal heart rate (FHR) decreased and variability increased. Thirty minutes before vaginal delivery, sudden fetal tachycardia (up to 210 beats per minute) was observed, with absent variability and minimal decelerations. At birth, the infant was apneic and hypotonic, but lacked biochemical evidence of acidemia or asphyxia; seizures developed in the early neonatal period. Subarachnoid hemorrhage was demonstrated by computed tomography of the head.

CONCLUSION

The occiput posterior position, marked molding, and prolonged labor with compulsive pushing may be associated with an increased risk of adverse outcome, even unrelated to the details of delivery. The change in FHR pattern, to a lowered baseline rate and increased variability, suggests increased intracranial pressure. The sudden change to fetal tachycardia with absent variability before delivery suggests intracranial hemorrhage or injury.

The ABCs of electronic fetal monitoring

There have been too many surrogates used to define fetal asphyxia and too many surrogates used to time fetal injury. Low Apgar scores and the need for prolonged resuscitation, by themselves, are inadequate criteria for the diagnosis of perinatal asphyxia or subsequent neurologic handicap. Even with the addition of a low cord pH and seizures, it is not possible to infer neurologic handicap. Furthermore, acidosis and depression at birth (which should be referred to as "perinatal asphyxia") cannot measure the duration and extent of any prenatal asphyxial encounter. Nor can we use the absence of one or more of these signs to exclude perinatal asphyxia as the cause of injury. We cannot refer to fetal asphyxia and injury therefrom without defining our criteria and describing the model of asphyxia being invoked. Because ischemia to the brain and other organs (that is, localized asphyxia), not systemic global asphyxia, appears to be the major precursor of human fetal injury it seems unreasonable to insist on systemic fetal asphyxia at any time to validate the timing or mechanism of fetal injury. Most hypoxic newborn infants are not injured and most injured newborn infants are not hypoxic. Furthermore, that a baby is injured as a result of hypoxia during labor does not mean that the hypoxia was preventable. FHR patterns, properly interpreted, may be one of the most reliable determinants of subsequent neurologic outcome and depending on the circumstances may provide insight into the timing and mechanism of neurologic injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal heart rate patterns and the timing of fetal injury

We studied the nonstress test (NST) results and other perinatal features of 44 children with cerebral palsy, who had fetal heart rate (FHR) patterns during labor suggesting preexisting injury. This was a retrospective, descriptive study. All fetuses persistently showed absent variability and small, variable decelerations, with overshoot from the onset of monitoring during labor. During the initial NST, 84.1% of fetuses revealed normal reactive NST patterns (three with decelerations). Six fetuses (15.9%) had nonreactive NST results (three with decelerations). The conversion of the reactive NST to a pattern of persistently absent variability often occurred during advanced pregnancy (average estimated gestational age 40 weeks), in association with decreased amniotic fluid (AF) volume (70.5%) and maternal complaints of decreased fetal movement (52.4%). FHR decelerations consistent with acute fetal distress were uncommon during early labor but occurred in about half of cases in advanced labor. All but one neonate had low Apgar scores at birth, but acidosis occurred in about one third of infants. Seizures developed in about half the infants, usually in the first day. Follow-up studies revealed a high incidence of mental retardation, microcephaly, and seizure activity in addition to cerebral palsy, regardless of the presence of perinatal acidosis. The results of this retrospective study of a limited population base suggest that fetal neurologic injury preceding labor may develop late in pregnancy, and that decreased AF volume appears to be a significant risk factor. FHR patterns may provide clues to the presence and timing of fetal neurologic injury.

The accuracy of auscultatory detection of fetal cardiac decelerations: a computer simulation

To evaluate current practices of auscultation for the detection of decelerations, we used a computer to generate contractions and late decelerations and perform the counting. The baseline rate ranged from 110 to 180 beats/min. The duration of the deceleration ranged from 1 to 2 minutes, and the amplitude of the deceleration ranged from 10 to 90 beats/min. The onset of the decelerations ranged from 0.4 to 0.7 of the length of the contraction. Counting was begun at 80%, 100%, and 120% of the contraction length. The duration of counting varied between 15 and 60 seconds. A multicount algorithm obtained three 10-second counts separated by 5 seconds. Results were classified by the ability to detect rates below 120, 100, or 80 beats/min (threshold determination) or 20 and 25 beats/min below the baseline rate (subtraction determination). The baseline rate and deceleration amplitude had the greatest effect on accuracy. The higher the baseline rate and the smaller the deceleration amplitude, the less accurate was detection. Multiple counts were more accurate than the single-count strategy, and subtraction detection was more accurate than threshold detection. The effects of counting error are briefly described. This model, which requires clinical confirmation, nevertheless emphasizes the potential inaccuracies of many popular schemes of auscultatory surveillance, even for the detection of prolonged or sustained decelerations. Certain modifications of auscultatory practice may improve the accuracy of this technique.

Community-based perinatal research

A program of clinical perinatal research was established in a community-based hospital in collaboration with private-practice obstetricians and their patients. This longitudinal study, undertaken to investigate the value of a circulating placental protein as an indicator of fetal compromise, enrolled 200 unselected pregnant patients. The project required collection of five blood samples at 16, 20, 24, 28, and 32 weeks' gestation in addition to a level II ultrasound examination at 32 weeks. Baseline and interim prenatal visit data were collected, as were maternal and neonatal data upon delivery. Patients who participated were invariably enthusiastic about their involvement. The physicians and their staff were also generally pleased. We infer from these and other studies a need to provide enhanced educational, participatory opportunities to all pregnant women. We conclude that properly conducted, reasonably funded projects that offer no direct benefit to the patient or physician can be successfully carried out with physicians and their private patients in community hospitals. The potential benefits of developing such extended resources can only enhance medical care and foster satisfaction and cooperation among physicians and patients.

Anencephalic infants: life expectancy and organ donation

Between 1978 and 1982, 205 anencephalic infants weighing more than 2,500 g were born alive in California. Although typically none were offered significant support, almost 9% lived more than one week. It seems reasonable to assume that modern intensive care would have increased survival times dramatically. In fact, preliminary data from centers specializing in neonatal organ transplantation demonstrate that seven to 14 days of ventilatory support can be accomplished for anencephalic infants without occurrence of brainstem death. Given these data and medical information that clearly establishes anencephalic infants as a "special case" of children who have not suffered brain death but could reasonably be used as organ donors, we believe that parents who wish to do so should be allowed to continue ventilatory support for their anencephalic children for whatever period of time is necessary to find organ recipients and arrange for organ donation. Arbitrary cutoff points for intensive care and artificial criteria for brain death should not be necessary to allow the use of anencephalic infants as organ donors. We believe that current laws should be changed to permit this scenario.

Perinatal antecedents of cerebral palsy

The dramatic reduction in perinatal morbidity and mortality over the last decade has not been accompanied by any diminution in the incidence of cerebral palsy. We investigated retrospectively the relationship of certain perinatal events to the subsequent development of cerebral palsy in 75 infants. Cerebral palsy occurred in association with acute intrapartum asphyxia in 8% and traumatic delivery in 11%. Thirty-five percent of cases were associated with chronic fetal distress, defined by a unique fetal heart rate (FHR) pattern consisting of a normal baseline rate with persistently absent variability and mild variable decelerations with overshoot. This pattern was found frequently in association with postmaturity, meconium staining, intrauterine growth retardation, and neonatal seizures. Acid-base studies, when available, did not reveal acidosis. Twenty-seven percent of the cases involved a combination of chronic fetal distress, acute intrapartum fetal asphyxia, and/or traumatic delivery. We postulate that antenatal intermittent umbilical cord compression secondary to oligohydramnios results in repetitive transient central nervous system ischemia, insufficient to cause death, but resulting in a characteristic FHR pattern and impaired neurologic development. If these data are confirmed, this FHR pattern may be an important marker for the development of subsequent neurologic handicap or other adverse outcome.

Pyelonephritis in pregnancy. The role of in-hospital management and nitrofurantoin suppression

Acute pyelonephritis remains a frequent complication of pregnancy. Prevention of the potential complications of this disease requires aggressive in-hospital management. However, the high frequency of positive outpatient cultures following discharge has cast doubt on the adequacy of in-hospital care and, at the same time, has concentrated attention on follow-up care. In a randomized, prospective study, we evaluated the effects of in-hospital management and outpatient nitrofurantoin on subsequent urine cultures. The overall frequency of positive cultures following discharge from the hospital was 38%. However, appropriate antibiotic selection, a negative follow-up in-hospital culture and nitrofurantoin suppression reduced the rate to 8% (P less than .01). Nitrofurantoin did not reduce the rate of positive cultures if antibiotic selection was inappropriate or if the in-hospital follow-up culture was positive. These results suggest that more aggressive management of acute pyelonephritis in pregnancy may be indicated and that suppressive therapy cannot compensate for inappropriate in-hospital management.

Acute oligohydramnios in postdate pregnancy

The evaluation of amniotic fluid volume plays a major role in antepartum fetal surveillance. Although the definition of diminished amniotic fluid volume varies, this sign is considered by itself an indication for intervention in the near-term fetus. The interval of testing is predicated on the concept that amniotic fluid volume diminishes slowly (unquantified) as a result of developing hypoxia. We present six postterm pregnancies in which amniotic fluid volume diminished abruptly over 24 hours. Although one fetus died, the three babies delivered by cesarean section and the two babies delivered after a 2-day labor did well, despite obvious postmaturity syndrome, meconium staining, and variable decelerations. Apgar scores in the survivors were above 8, and pH results failed to confirm hypoxia. These data suggest the need to better understand the mechanisms regulating amniotic fluid volume.

Fetal cardiac asystole during labor

A review of 14 cases of fetal cardiac asystole greater than two seconds during labor revealed two distinct patterns. Type 1 episodes developed without warning in eight apparently healthy fetuses at the nadir of a variable deceleration. These episodes were both preceded and followed by normal to increased variability, stable baseline heart rate, and less dramatic variable decelerations. Analysis of the fetal electrocardiogram (ECG) complexes during the asystole revealed a normal QRS complex, either biphasic or absent P-waves, and occasional ventricular extrasystoles. One of eight fetuses in this group died; the remainder were delivered in good condition and required minimal resuscitation. The mechanism of type 1 episodes appears to be an exuberant vagal response to umbilical cord compression. Rapid intervention probably is not warranted. Type 2 episodes developed in seriously asphyxiated infants and frequently were preceded by absent variability and, usually, severe decelerations. The fetal ECG pattern during the episode revealed bradycardia with sinus rhythm. Five of the six infants with type 2 episodes died either in utero or in the neonatal period. Despite the ominous portent of type 2 patterns, rapid delivery appears to be indicated.

Electronic fetal monitoring and obstetrical malpractice

The standard of care with regard to any new medical technology develops slowly. Attitudes must change, and equipment must be purchased, installed and utilized. Technical problems must be resolved and protocols established. Advances are better understood and more aggressively pursued by some physicians than others, with a consequent disparity in implementation. Electronic fetal monitoring (EFM) is an example of such a technology. Little known to obstetricians 15 years ago, EFM has been accepted by practitioners widely and rapidly. Today, armed with guidelines from the American College of Obstetricians and Gynecologists (ACOG) and the recommendations of the National Institutes of Health (NIH), we monitor with EFM most obstetrical patients during labor and almost all high-risk patients before labor. While the practice or custom of a majority of obstetricians does not necessarily define the standard of care, the use of EFM for fetal surveillance during labor represents the prevailing medical and legal standard of care.