The effect of variable heart rate decelerations on intraventricular hemorrhage and other perinatal outcomes in preterm infants.

OBJECTIVE: We investigated the hypothesis that repetitive variable heart rate decelerations in labor are associated with an increased incidence of neonatal complications in premature infants. METHODS: This was a retrospective case-control study. Singleton fetuses weighing between 750 and 2500 g at 25-35 weeks' gestation were considered for the study. Fetuses delivered by Cesarean section prior to labor were excluded. Heart rate traces were retrieved from an electronic archive and were assessed for the presence of variable decelerations. Cases had at least three variable decelerations in the hour prior to delivery and were matched 1:1 with controls for gestation, sex and birth weight. RESULTS: A review of 6500 deliveries yielded 41 matched pairs. The groups were compared for the following outcomes. Measures of acute morbidity were cord pH at delivery, 5-min Apgar score and resuscitation; measures of chronic morbidity were intraventricular hemorrhage, periventricular leukomalacia, necrotizing enterocolitis and death. There was no difference in measures of acute morbidity between the groups. The incidence of chronic morbid outcome measures in the cases was six (15%) vs. one (2.5%) in controls (p = 0.01). CONCLUSIONS: This study suggests that variable decelerations in preterm infants are associated with chronic morbidity, particularly intraventricular hemorrhage through a mechanism independent of fetal acidemia. Further study is required to determine whether these infants would benefit from early Cesarean section.

The effect of income pooling within a call group on rates of obstetric intervention.

BACKGROUND: On July 1, 1997, the call group at a tertiary referral hospital in Ottawa changed its remuneration. The authors tested the hypothesis that change in an obstetric call group's remuneration from individual fee-for-service billing to equal sharing of the pooled group income would result in reduced rates of obstetric intervention. METHODS: Intervention rates were compared for the 12 months before (1678 births) and the 12 months after (1934 births) the change. Data were collected on onset of labour, indication for induction of labour, mode of delivery and neonatal outcome. Statistical analysis was performed with Wilcoxon's signed-rank test. RESULTS: The mean rate of elective induction of labour was 38.6% in the year before the change and 33.3% in the year after the change (p = 0.01). There were small but statistically significant increases in the mean duration of labour and mean length of the second stage (p = 0.03). INTERPRETATION: Billing policy may affect clinical decisions. Our findings add weight to the literature showing increased intervention rates with fee-for-service remuneration.

The relationship between cervical dilatation at initial presentation in labour and subsequent intervention.

OBJECTIVE: To examine the relationship between the cervical dilatation at which women present in labour and the subsequent likelihood of caesarean section. DESIGN: Retrospective cohort study. SETTING: University teaching hospital. POPULATION: 3,220 women met the entry criteria from 14,050 deliveries between January 1995 and December 1999. METHODS: Women meeting the following criteria were identified: those in spontaneous labour with a singleton pregnancy and a cephalic presentation at 37-42 weeks of gestation; all women delivering within 36 hours of first presentation were included. Women who had spontaneous rupture of the membranes before first attendance were excluded. MAIN OUTCOME MEASURES: The primary outcome was the rate of caesarean section. Secondary outcomes were operative vaginal delivery, fetal weight, cord pH, five minute Apgar score, length of labour, labour augmentation with oxytocin and epidural analgesia. RESULTS: The risk of caesarean section decreased with increasing cervical dilatation at presentation. This was true for nulliparous (n = 1,168) and parous women (n = 2,052). The caesarean section rate of nulliparous women presenting at 0-3cm (n = 812) was 10.3%, compared with 4.2% for those presenting at 4cm-10 cm (n = 356), and the mean duration of labour before presentation was 2.0 hours versus 4.5 hours, respectively (P = 0.0001). For parous women the caesarean section rates were 5.7% and 1.3%, respectively (P = 0.0001). There were significantly greater frequencies of use of oxytocin and epidural analgesia by women presenting earlier in labour. The caesarean section rate of 185 nulliparae (15.8%) who were initially allowed home was no different from those admitted immediately (9.2% vs 8.2%, P = 0.67). Similarly, 196 (9.5%) of multiparae went home and had a caesarean section rate of 3.6%, compared with 3.1% if admitted immediately (P = 0.76). CONCLUSIONS: Women who present to hospital at 0-3cm spend less time in labour before presentation and are more likely to have obstetric intervention than those presenting in more advanced labour. Outcomes were similar whether or not the woman was initially allowed home.

Accuracy of strategies for monitoring fetal heart rate in labor.

We investigated whether the accuracy of auscultation could be improved with the use of a heart rate meter. Six fetal heart rate (FHR) traces were presented in a random sequence to 30 subjects using a customized computer program in each of three modalities: auscultation by counting alone, auscultation with the aid of an FHR meter, and visual assessment. The following characteristics were assessed: baseline rate, baseline variability, periodic change, and interpretation of the trace. For baseline rate, counting was associated with consistent underestimation of the FHR, which became more evident as the heart rate increased. The variation observed with each method was greatest with counting. For baseline variability, the proportion of correct responses using a meter was comparable to visual assessment, whereas counting was significantly less effective in 4 of 6 traces. For periodic change, the use of a meter was superior to counting in 4 of 6 traces, but both were inferior to visual assessment in 4 of 6 traces. In the interpretation of the trace, the use of a meter was again superior to counting, but both were inferior to visual assessment. Discrepancies were most marked in the least reassuring traces. Assessment of the FHR is significantly more accurate with the aid of a heart rate meter, and reduces interobserver variation.

Power spectral analysis of fetal heart rate.

This chapter examines the role of power spectral analysis (PSA) in elucidation of the physiological control mechanisms of fetal heart rate and as a potential indicator of fetal well-being. The importance of fetal heart rate variability (FHRV) as an indicator of fetal oxygenation is discussed, and the limitations in the current methods of measurement of FHRV are highlighted. Evidence is presented for the paramount influence of the autonomic nervous system in the control of heart rate variability. The basic proposition underlying spectral analysis is that the two autonomic branches influence heart rate in a frequency-dependent way, and their differential effects can be determined by PSA which breaks down the heart rate trace into its component frequencies. The application of PSA to heart rate variability data is an established tool in cardiology, and the published literature related to its use in the adult, neonate and fetus is reviewed. The power spectrum is sensitive to the activity state of the fetus, particularly fetal breathing movements, which have a variable effect on short- and long-term FHRV. There are a variety of mathematical approaches to the construction of power spectra, and a particular method of data acquisition and analysis is presented together with some theoretical background. Recent experimental evidence indicates a role for PSA as an indicator of fetal activity state, and the effect of hypoxia on the spectrum of the fetus in labour is discussed. There are some problems with the technique of PSA, particularly in regard to accepted definitions and methods of analysis. It is a powerful non-invasive tool in the elucidation of fetal cardiac control, but its value in the detection of the compromised fetus has yet to be tested in a clinical trial.

Cardiac electromechanical dissociation in the hypoxic fetal sheep may have clinical implications.

OBJECTIVES: Our purpose was to determine the sequence of fetal cardiac electrical and mechanical events associated with acute hypoxic acidemia and to correlate those events with terminal fetal heart rate patterns preceding fetal death. STUDY DESIGN: Eight acutely catheterized fetal sheep were rendered hypoxic by placental embolization with microspheres until fetal death occurred. The fetal electrocardiogram, Doppler cardiogram, left ventricular and aortic pressures, and fetal heart rate were continuously recorded. RESULTS: All eight fetuses showed a terminal bradycardia consisting of two phases: an initial phase of falling ventricular pressures, culminating in mechanical asystole, and a subsequent phase after asystole during which the electrocardiographic signal persisted for an average duration of 15.2 +/- 8.7 minutes (range 3.1 to 32.4) and triggered a Hewlett-Packard 8040A monitor to show a heart rate pattern. CONCLUSIONS: The phenomenon of cardiac electromechanical dissociation may be occurring during similar terminal bradycardias that are observed in human labor and explains the delivery of a fresh stillbirth in spite of the recording of an electrocardiographic signal from a scalp electrode.

What is a low-lying placenta?

Transvaginal ultrasonography was performed in 127 women thought to have placenta previa. In all cases of complete previa, placental location was confirmed at cesarean section. Where the placenta was situated in the lower segment of the uterus but did not cover the cervical os the distance from the placental edge to the internal cervical os was measured. This distance was analyzed in relation to the route of delivery. No patient with a placental edge greater than 2 cm from the internal cervical os required cesarean section for the indication of placenta previa, whereas seven of eight patients with a distance of less than or equal to 2 cm underwent cesarean section because of bleeding characteristic of a placenta previa. These preliminary results suggest that transvaginal ultrasonography measurement may indicate the optimal delivery route and make the traditional classification of placenta previa obsolete.

The aetiology of vaginal bleeding in children. A 20-year review.

The cause of vaginal bleeding in girls of 10 years and under is reviewed. Of the 52 patients seen, in 28 (54%) bleeding was caused by a local lesion and 11 (21%) of these had malignant genital tumours. Eleven (21%) children presented with some form of precocious puberty, and in 13 (25%) patients no cause could be found.

The duration of lochia.

The duration of lochia and its association with a number of obstetric variables was studied in 236 women. Each woman completed a diary sheet describing the colour and duration of her lochia for up to 60 days post partum. The phases of lochia were divided according to the classical description; lochia rubra, serosa and alba. The median total duration of lochia was 33 days, lochia rubra 4 days and lochia serosa 22 days. Lochia persisted to 60 days in 13% of women. The duration of lochia was shorter in parous women and women with smaller babies.