Robert E. Petres

Clinical application of a scoring system for evaluation of antepartum fetal heart rate monitoring

Five hundred-seven passive tests (PTs) on 260 patients and 133 oxytocin challenge tests (OCTs) on 97 of these patients were reviewed. The tracings were categorized according to a proposed modified scoring system based on baseline fetal heart rate (FHR), variability, accelerations and decelerations of FHR, and fetal activity. The scoring system was compared with the usual criteria for fetal compromise currently employed in PTs and OCTs and was found to be superior in accuracy. The usefulness of antepartum FHR monitoring as evaluated throuth the scoring system is discussed. It is concluded that passive testing can largely replace the OCT.

Intrapartum fetal heart rate monitoring: VIII. Atypical variable decelerations

A total of 1,996 fetal heart rate (FHR) tracings were analyzed to assess the prognostic significance of variable decelerations. Nineteen percent (186 cases) of 988 tracings with variable decelerations in the last 30 minutes of monitored labor exhibited signs of atypia listed in order of frequency: (1) loss of initial acceleration, (2) slow return to the baseline FHR, (3) loss of secondary acceleration, (4) prolonged secondary acceleration, (5) biphasic deceleration, (6) loss of variability during deceleration, and (7) continuation of the baseline at a lower level. Variable decelerations with one or more of these features were called atypical variable decelerations and predicted a high incidence of fetal acidosis and low Apgar scores. By contrast, adverse fetal outcome was uncommon with pure variable decelerations (p much less than 0.001) irrespective of the duration and amplitude of the deceleration. Both pure and atypical variable decelerations were associated with other FHR abnormalities in over 60% of the cases. However, the particularly unfavorable combination with decreased FHR variability and tachycardia or bradycardia was seen more frequently with atypical than with pure variable decelerations (p much less than 0.001) and predicted the highest incidence of low Apgar scores. It is concluded that atypical features aid greatly in the identification of distress in fetuses with variable decelerations.

Intrapartum fetal heart rate monitoring: III. Association of meconium with abnormal fetal heart rate patterns

Fetal heart rate (FHR) tracings of 284 fetuses with meconium-stained amniotic fluid (MSAF) and 1,672 fetuses without meconium staining were compared to investigate the significance of meconium associated with normal and abnormal FHR patterns. MSAF was found to be associated with significantly more low 1- and 5-minute Apgar scores and higher neonatal mortality rates than the control group without meconium. An increase in abnormal FHR patterns in the MSAF group over the control group as well as the postpartum sequelae of meconium itself was likely responsible for the unfavorable outcome. It is concluded that the presence of meconium should be viewed as a warning sign of fetal distress which warrants close intrapartum observation of the patient.

Intrapartum fetal heart rate monitoring: VI. Prognostic significance of accelerations

The fetal heart rate (FHR) tracings of 1,996 fetuses were analyzed to assess the prognostic value of accelerations in early labor and just prior to delivery. Accelerations were divided into periodic and sporadic types according to their association or lack of association with uterine contractions. It is shown that two or less sporadic accelerations per 30 minutes are unfavorable. Three accelerations indicate fetal well-being as much as any higher number of accelerations per 30 minutes. FHR abnormalities coexistent with three or more sporadic accelerations were found to have a better prognosis than FHR abnormalities associated with two or less sporadic accelerations. Fetuses exhibiting low FHR variability commonly showed lack of accelerations, whereas normal FHR variability was almost invariably accompanied by sporadic accelerations. The pathogenesis of accelerations is discussed. It is concluded that accelerations are indicators of fetal well-being, whereas the lack of accelerations with lack of reactivity to manipulation of the fetus may be indicative of severe fetal hypoxia with fetal acidemia. This conclusion is supported by fetal outcome and determination of pH from fetal scalp blood.

Intrapartum fetal heart rate monitoring: V. Fetal heart rate patterns in the second stage of labor

A total of 1,755 fetal heart rate (FHR) tracings of the second stage of labor was analyzed. The FHR patterns were classified according to the behavior of the baseline FHR and are listed in decreasing order of benignity: normocardia, transitory bradycardia, tachycardia, persistent bradycardia, and progressive bradycardia. Each category was further subdivided into four groups on the basis of association or nonassociation with early, variable, or late decelerations. Cord compression pattern were noted in over 50% of the FHR tracings and account for the majority of low Apgar scores and fetal acidosis. FHR abnormalities occurred in 91% of second-stage labor patterns, and were mild in most cases or of too short duration to influence fetal outcome. An effort was made to establish therapeutic guidelines based on the morphologic features, prognostic grading, and the etiology of the FHR patterns in the second stage of labor.

Intrapartum fetal heart rate monitoring: II. Multifactorial analysis of intrapartum fetal heart rate tracings

The first 30 minutes and the last 30 minutes of 1,996 intrapartum FHR tracings were analyzed for baseline FHR, variability (amplitude and frequency of oscillations), accelerations, and decelerations. A modified FHR scoring system incorporating these FHR features was employed. According to the association between various FHR scores and the incidence of low Apgar scores, FHR patterns were grouped into three basic categories with distinct prognostic significance: (1) normal FHR patterns, (2) compensated distress patterns, and (3) decompensated distress patterns. It is concluded that the prognostic significance of FHR tracings is increased by incorporating several FHR monitoring criteria in the analysis.

Intrapartum fetal heart rate monitoring. IV. Observations on elective and nonelective fetal heart rate monitoring.

Heart rate tracings and outcome in 919 electively and 1,077 nonelectively monitored fetuses were compared in order to investigate the value of elective surveillance of the fetal heart rate (FHR) in either group. A threefold higher perinatal mortality and a twofold higher number of low 5-minute Apgar scores were observed among patients with risk factors compared to electively monitored pregnancies. In the beginning of monitored labor, fetuses with risk factors exhibited a higher incidence of FHR patterns with low FHR variability than fetuses without risk factors. In the final phase of labor, FHR patterns indicative of hypoxia, i.e., late decelerations and severe and atypical variable decelerations, were found more often in the nonelective than in the elective group. Umbilical cord problems reflected by the occurrence of variable deceleration were responsible for the majority of low Apgar scores observed among electively monitored fetuses. The findings and their implications for FHR monitoring are discussed.

Reversal of acute polyhydramnios after fetal renal decompression

Polyhydramnios and premature labor at twenty-seven weeks secondary to an intrafetal renal cyst are described. Antenatal fetal cyst decompression successfully reversed the polyhydramnios and prevented premature delivery, resulting in a full-term healthy infant delivered vaginally at thirty-nine weeks. Urologic investigation postpartum revealed a probable congenital ureteropelvic junction obstruction.

Intrapartum fetal heart rate monitoring. VII. The impact of mode of delivery on fetal outcome.

The condition of 1,991 fetuses just prior to delivery was assessed in a semiquantitative manner by means of a fetal heart rate (FHR) score. A comparison between types of delivery was made for groups with identical FHR scores to test the hypothesis that the differences in lower Apgar score rates were consequences of the type of delivery rather than differences in prenatal condition. For each of several FHR scoring categories, the differences in rates of low Apgar scores between spontaneous vaginal deliveries and cesarean sections were consistently different in favor of the vaginally delivered group. No such difference was observed when spontaneous vaginal deliveries were compared with low-forceps deliveries. Breech deliveries, when compared to spontaneous vaginal deliveries, resulted in a higher rate of low 1-minute Apgar scores. Five-minute Apgar scores were significantly different only if the breech delivery was preceded by abnormal FHR patterns.