Electronic fetal monitoring: past, present, and future

Electronic fetal monitoring (EFM) using cardiotocography is a common tool used during labor and delivery for assessment of fetal well-being. It has largely replaced the use of intermittent auscultation and fetal scalp pH sampling. However, data suggesting improved clinical outcomes with the use of EFM are sparse. In this review, the history of EFM is revisited from its inception in the 1960s to current practice, interpretations, and future research goals.     

Electronic Fetal Monitoring: Is It of Benefit?

ABSTRACT: Electronic fetal monitoring (EFM) of the fetal heart rate during labor and delivery has become a cornerstone of the new technology of obstetrics. Its routine use has been advocated, and the majority of labors in the U.S. are now monitored electronically. Recently, questions have been raised about the benefits of EFM. Review of the literature shows that only 4 randomized controlled clinical trials (RCTs) of EFM have been carried out. These show little if any benefit from the use of EFM in comparison to monitoring by stethoscope (fetoscope). The lack of diagnostic precision of EFM is reflected in high false positive and false negative rates of identification of fetuses in distress. Although many retrospective studies of EFM attempt to correlate use of EFM with declines in perinatal mortality in specific hospitals, the 4 RCTs showed no difference in mortality between babies monitored by auscultation and those who were electronically monitored. No differences have been found in morbidity, including neurologic status, between infants in the two groups. Electronic fetal monitoring has been associated with a significant increase in the cesarean section rate in most retrospective studies and all the RCTs.     

Whither electronic fetal monitoring?

Largely based on promising animal studies, continuous electronic fetal monitoring (EFM) was introduced into clinical practice in the early 1970s. After almost 20 years of experience, it is now apparent that the anticipated benefits of this technology have not materialized. Undesirable side effects of EFM include inappropriate operative intervention for some patients and increased liability for physicians and hospitals, resulting in an increase in the costs of obstetric services. After reviewing several research studies, The American College of Obstetricians and Gynecologists concluded that EFM and intermittent auscultation are equivalent methods for intrapartum assessment. We have developed a protocol for the performance of intermittent auscultation, including indicated responses to different levels of bradycardia. This protocol has allowed us to substitute auscultation for EFM in a high percentage of patients using existing nursing personnel. Laboring patients should, at a minimum, receive information on both intermittent auscultation and EFM to enable them to make an informed choice of method for intrapartum fetal assessment.     

Mothers' Views of Continuous Electronic Fetal Heart Monitoring and Intermittent Auscultation in a Randomized Controlled Trial

ABSTRACT: We report the views of 200 women interviewed as part of a large randomized controlled trial in a Dublin hospital to compare a policy of continuous intrapartum fetal heart rate monitoring (EFM) with an alternative policy of intermittent auscultation using a Pinard stethoscope (IA). More women allocated to EFM reported that they felt restricted in their movements than did those allocated to IA. On the other hand, we found no evidence that the method of monitoring either influenced the support that they said they experienced or provided significant reassurance or made them feel more or less in control. There is a suggestion that women monitored with EFM were more likely to be left alone for short periods. This study suggests that the method of monitoring was less important to women in this hospital than the support and reassurance they received from staff and companions. Personal and continuous care from a midwife for all women in labor is a key feature of the hospital's policy and our study suggests that, in general, this policy was successfully translated into both IA and EFM practice, although the association between the use of EFM and an increase in women being left alone for short periods indicates a need for caution.     

RESPONSES OF LABORING WOMEN TO FETAL HEART RATE MONITORING

Authors of 13 studies agreed that women generally felt positively about the method of fetal monitoring they experienced during labor, whether intermittent auscultation (AUS) or electronic fetal monitoring (EFM). Advantages and disadvantages of both AUS and EFM are discussed. Limitations of the research are discussed, and clinical suggestions are given for ways the nurse-midwife can accent the advantages and minimize the disadvantages of whatever method is chosen.     

Monitoring the fetus in labor: evidence to support the methods

Electronic fetal monitoring (EFM) was implemented across the United States in the 1970s. By 1998, it was used in 84% of all U.S. births, regardless of whether the primary caregiver was a physician or a midwife. Numerous randomized trials have agreed that continuous EFM in labor increases the operative delivery rate, without clear benefit to the baby. Intermittent auscultation (IA) is safe and effective in low-risk pregnancies and may play a role in helping birth remain normal. Clinicians and educators are encouraged to reconsider the use of IA in the care of healthy childbearing women.     

Maternal attitudes to fetal monitoring

During a randomized clinical trial concerning alternative methods of intrapartum fetal surveillance (electronic fetal monitoring (EFM) and auscultation (AUS)) an investigatory interview was carried out. Out of 655 expecting mothers the antepartum preference of EFM was 39.5%, of AUS 32.3% and 28.1% were undecided (UD). EFM was especially preferred by obstetrical high-risk patients. Reasons for preference of AUS were a natural childbirth, a non-technological milieu, and the lack of supposed discomfort from sensors and belts. The pregnant women found as major advantages of EFM continuous observation and the possibility of quick intervention. Postpartum 385 patients were again interviewed. The majority upheld the original preference if that method was used. If the non-preferred method had been applied many would stick to the primary preference although a tendency to prefer the experienced method was seen. The patients who antepartum preferred AUS, but had EFM, became more positive toward the method, and a significantly increased number were positively influenced by the EFM signal/trace and found the method promoting their partner's involvement in labor. Enforced immobility, however, was a major disadvantage as well as the technical milieu. If EFM is to be accepted by a majority of women giving birth it is necessary to increase the pregnant women's knowledge of the method and to take milieu factors into consideration in order to reduce the intrinsic depersonalization of EFM.     

Electronic Fetal Monitoring During Premature Labor and the Occurrence of Perinatal Mortality in Very Low Birthweight Infants

ABSTRACT: The efficacy of intrapartum electronic fetal heart rate monitoring (EFM) in reducing perinatal mortality is uncertain. In a multihospital study in King County, Washington, we compared the effect of EFM with periodic auscultation in singleton infants with birthweights of 700 to 1500 g. Charts were reviewed for all 304 such pregnancies delivered during 1977-1979 at the 14 area hospitals that provide obstetric care. The group with periodic auscultation showed a relatively higher proportion of risk factors for perinatal mortality: extremely low birthweight (< 1100 g), noncephalic presentation, delivery outside a tertiary obstetric center, and absence of premature rupture of membranes. Adjusted for these risk factors, the perinatal mortality of the EFM group was only slightly less than that of the group with periodic auscultation (relative risk = 0.91; 95% confidence limits = 0.65–1.3). Our results suggest that in infants of very low birthweight, the probability of perinatal death is little affected by the choice of EFM or periodic auscultation to monitor fetal heart rate.     

Aspects of FHR tracings as warning signals

We have reviewed several different groups of common clinical problems with an eye toward their effects on FHR tracings. Although argument exists in the literature concerning the universal applicability of continuous EFM, most authors agree that continuous EFM is desirable, if not imperative, within these subgroups. Schifrin said, "It appears that potential benefits accrue when EFM and scalp sampling are employed with understanding and adequate training." With appropriate training, EFM and pH analysis can help the clinician to quickly and accurately assess fetal condition and to make necessary decisions regarding labor and delivery. The interpretation of fetal monitoring patterns necessitates consideration of gestational age and maternal condition as a starting point in analysis. The many other components of fetal-maternal interactions that occur with labor and delivery can be assessed satisfactorily only in this light.     

The Dublin randomized controlled trial of intrapartum fetal heart rate monitoring

In a randomized controlled trial involving 12,964 women, a policy of continuous electronic intrapartum fetal heart monitoring was compared with an alternative policy of intermittent auscultation, both policies including an option to measure fetal scalp blood pH. Women allocated to electronic fetal heart monitoring had shorter labors and received less analgesia. The caesarean delivery rates were 2.4% for electronic fetal heart monitoring and 2.2% for intermittent auscultation but this small difference arose from the identification of nearly twice as many fetuses with low scalp pH (less than 7.20) in the electronic fetal heart monitoring group. The forceps delivery rate was 8.2% in the electronic fetal heart monitoring group compared with 6.3% in the intermittent auscultation group, and this excess was explained by more instrumental deliveries prompted by fetal heart rate abnormalities. There were 14 stillbirths and neonatal deaths in each group, with a similar distribution of causes. There were no apparent differences in the rates of low Apgar scores, need for resuscitation, or transfer to the special care nursery. Cases of neonatal seizures and persistent abnormal neurological signs followed by survival were twice as frequent in the intermittent auscultation group, and this differential effect was related to duration of labor. Follow-up at 1 year of babies who survived neonatal seizures revealed three clearly abnormal infants in each group. The implications of these findings for both theory and practice are discussed.     

Obstetrical Nurses' Attitudes Toward Fetal Monitoring

A 24-item tool, using a Likert attitudinal scale, was developed to measure labor and delivery nurses' attitudes toward fetal monitoring and was administered to 124 nurses. For each of the 24 attitude statements, cumulative responses were over 50% positive at least. Fifty-two percent of the nurses felt that routine continous monitoring of all labor patients would he ideal, and 88% felt that the fetal survillance achieved by monitoring cannot he matched by intermittent auscultation.     

Use of diagnostic ultrasound, X-ray examinations, and electronic fetal monitoring in perinatal medicine

Obstetrical technologies such as electronic fetal monitoring (EFM) and selected diagnostic imaging procedures can be integral components of perinatal care. The Center for Devices and Radiological Health, a unit within the Food and Drug Administration, collaborated with the National Center for Health Statistics in the design and conduct of a National Maternal and Infant Health Survey to collect information from prenatal care providers, hospitals, and mothers on the use of EFM, diagnostic ultrasound, and x-ray examinations during pregnancy, labor, and delivery. A pretest, conducted some months before the survey began, showed that 78.8% of the pregnancies surveyed received a diagnostic ultrasound examination during pregnancy. Approximately 58.3% of the ultrasound-exposed mothers had two or more such examinations. Approximately 10.1% of the ultrasound examinations were performed in the first trimester of pregnancy, 57.0% in the second trimester, and 32.9% in the third trimester. The most common indication for an ultrasound examination was to establish dates or gestational age. Approximately 15.3% of the pregnancies surveyed received an x-ray examination. Approximately 74.6% of the pregnancies were monitored with EFM during labor. External EFM was used alone during 54.9% of the labors and along with internal EFM during 19.7% of the labors. The implications of these pretest findings are discussed, along with a review of the medical literature on the safety and effectiveness of these medical device technologies.     

What is the gold standard for intrapartum fetal monitoring?

The health authorities of Stockholm county recently published a Health Technology Assessment report: "Fetal monitoring with computerized STAN analysis during labor - a systematic review" with the aim to ensure that high quality research information on costs, effectiveness and broader impact of health technologies is analysed and presented in the most efficient way for those who use, manage and work in this field. The report claims to analyse available research in relation to ST interval analysis of fetal electrocardiogram (STAN) and concludes that scientific evidence for advantages of the STAN technology for maternal and fetal outcome was insufficient and that clinical use cannot be recommended and should be restricted to research protocols. The Norwegian reference group for fetal surveillance points out that the report suffers from two insufficiencies: selection bias by not providing a complete collection of the evidence for the clinical performance of the STAN technology and, secondly, that it does not provide evidence-based alternative methods.     

Are Routine Interventions Necessary in Normal Birth?

Routine interventions during labor and birth, such as perineal shaving and enemas before vaginal delivery, continuous intrapartum electronic fetal monitoring (EFM), and episiotomy are prevalent in Taiwan, but they may not always be necessary. Numerous studies investigating these interventions have failed to find absolute benefits for women with uncomplicated and low-risk pregnancies. No evidence-based benefits support routine perineal shaving or enemas during labor for reducing the risk of perineal wound infection or neonatal infection. The use of EFM is associated with an increased rate of operative interventions (vacuum, forceps, cesarean delivery) but does not result in a significant decrease in the incidence of perinatal death or cerebral palsy. Routine episiotomy does not have demonstrable advantages over restrictive episiotomy in the frequency or severity of perineal damage or pelvic relaxation.     

Acute fetal distress

Three different clinical patterns of acute fetal distress may be observed during labor: an ante-partum hypoxia with a persistent nonreactive and "fixed" fetal heart rate (FHR) on admission to the hospital, a progressive intra-partum asphyxia manifested, as the labor continues, by a substantial rise in baseline heart rate, a loss of variability and repetitive severe variable or late decelerations, and finally, as a result of a catastrophic event, a sudden prolonged FHR deceleration to approximately 60 beats per minute lasting until delivery. However the majority of fetuses with nonreassuring tracings of FHR are neurologically intact, as evidenced by the high false-positive rate of electronic fetal monitoring (EFM). Therefore the diagnosis of fetal distress must be corroborated by complementary methods, such as continuous recording of the fetal electrocardiogram or computed-assisted EFM, fetal pulse oximetry or fetal scalp sampling with immediate determination of blood gases or lactates. Defavorable outcome of an acute fetal distress leading to neonatal encephalopathy or death is best predicted by a persisting low Apgar score (<3) for more than 5 minutes and by a severe metabolic acidosis (umbilical artery pH<7,00 and base-excess>-12mmol/l).     

Labor induction versus expectant management for postterm pregnancies: a systematic review with meta-analysis

OBJECTIVE: To compare routine labor induction with expectant management for patients who reach or exceed 41 weeks' gestation. DATA SOURCES: Computerized databases, references in published studies, and textbook chapters in all languages were used to identify randomized controlled trials (RCTs) evaluating induction and expectant management of labor for postterm pregnancies. METHODS OF STUDY SELECTION: We identified RCTs that compared induction and expectant management for uncomplicated, singleton, live pregnancies of at least 41 weeks' gestation and evaluated at least one of the following: perinatal mortality, mode of delivery, meconium-stained fluid, meconium aspiration syndrome, meconium below the cords, fetal heart rate (FHR) abnormalities during labor, cesarean deliveries for FHR abnormalities, abnormal Apgar scores, and neonatal intensive care unit (NICU) admissions. The primary outcomes assessed were cesarean delivery rate and perinatal mortality. TABULATION, INTEGRATION, AND RESULTS: Sixteen studies met inclusion criteria for this review. For each study with binary outcomes, an odds ratio (OR) with 95% confidence intervals (CIs) was calculated for selected outcomes. Estimates of ORs for dichotomous outcomes were calculated using fixed and random-effects models. Homogeneity was tested across the studies. Compared with women allocated to expectant management, those who underwent labor induction had lower cesarean delivery rates (20.1% versus 22.0%) (OR 0.88; 95% CI 0.78, 0.99). Although subjects whose labor was induced experienced a lower perinatal mortality rate (0.09% versus 0.33%) (OR 0.41; 95% CI 0.14, 1.18), this difference was not statistically significant. Similarly, no significant differences were noted for NICU admission rates, meconium aspiration, meconium below the cords, or abnormal Apgar scores. CONCLUSION: A policy of labor induction at 41 weeks' gestation for otherwise uncomplicated singleton pregnancies reduces cesarean delivery rates without compromising perinatal outcomes.     

WHAT THE DUBLIN TRIAL SUGGESTS ABOUT BENEFITS; WHAT COMMENTS SUGGEST ABOUT WHO SHOULD INTERPRET THE TRACINGS

The Dublin Trial will probably not alter firmly held beliefs about whether electronic fetal monitoring (EFM) is better than auscultation. The neonatal seizures that EFM apparently prevented were those that did not result in serious neurologic deficit at 1 year of age. If, as had been suggested, EFM tracings are hardly ever correctly interpreted, then EFM should hardly ever be used.     

产时Ⅱ类胎心监护的流程管理

Ⅱ类胎心监护是产程中常见的胎心监护图形，其形式多样，正确识别和评估Ⅱ类胎心监护，并根据具体临床情况进行针对性干预，可降低不良妊娠结局的发生。文章根据产时胎心监护三级评估系统，介绍产时Ⅱ类胎心监护的处理流程，并对不同类型Ⅱ类胎心监护的病因及干预措施进行了阐述，以指导临床实践。