Intrapartum Fetal Heart Rate Tracings Research Articles

Intrapartum fetal heart rate tracings: accuracy of interpretation is unaffected by level of providers’ training

Objective: The ACOG Technical Bulletin of July 1995 suggests that intrapartum fetal heart rate patterns should be interpreted as reassuring or nonreassuring. The bulletin describes a nonreassuring fetal heart tracing (FHT) as having one or more of the following components: abnormal baseline (ie, tachycardia, decreased variability); the presence of variable decelerations that are persistent, progressively deeper and longer lasting; late decelerations that are persistent; prolonged deceleration greater than 60 seconds; and a sinusoidal heart rate pattern. A reassuring FHT implies the absence of these patterns. We sought to investigate the accuracy of interobserver interpretation of FHT in labor. Method: Three hundred sixty intrapartum FHTs were evaluated by obstetric residents, attendings, nurses, and maternal–fetal medicine specialists (MFMs). Tracings were accompanied by a questionnaire addressing classification of FHT, a proposed approach, and anticipated fetal outcome. Participants were blinded to actual outcomes. Results: 1) Of reassuring FHTs, 96% were identified with no significant difference in rate of identification in each provider group; 2) 80% of nonreassuring patterns were identified with similar rates of identification within each provider group; and 3) there was no significant interobserver difference in the correct interpretation of tracings between residents (75.5%), attendings (81.9%), MFMs (77.4%), and nurses (85%). Conclusion: Our data suggest that theTechnical Bulletin’s recommended classification of intrapartum FHT tracings as reassuring versus nonreassuring is successful in providing a simple, accurate method of recognition regardless of the providers’ level of obstetric training.

A comparison of visual analyses of intrapartum fetal heart rate tracings according to the new National Institute of Child Health and Human Development guidelines with computer analyses by an automated fetal heart rate monitoring system

Objectives: The aim of this study was to compare the visual analyses of fetal heart rate tracings by observers according to recent National Institute of Child Health and Human Development interpretative guidelines both with each other and with those of a computerized fetal heart rate analysis and alerting system. Study Design: One-hour sections of intrapartum fetal heart rate records were analyzed by a computerized monitoring system (Hewlett-Packard TraceVue; HP GmbH, Böblingen, Germany) and by 4 observers (a registered obstetric nurse, a certified nurse-midwife, an obstetrics resident physician, and a physician maternal-fetal medicine faculty member) instructed to use the new National Institute of Child Health and Human Development guidelines. We compared specific alerts, baseline rates, frequencies of accelerations and decelerations, and signal quality assessments generated by the TraceVue system and the observers. Power analysis indicated that 50 tracings were required to detect interobserver and observer-computer agreement levels of 80% ± 10%. Statistical comparisons used κ coefficient, χ2 test, and analysis of variance with repeated measures as appropriate. Results: Levels of agreement between observer pairs and the computer did not vary significantly across successive 10-minute intervals. Overall levels of interobserver agreement for baseline rate, tracing quality assessment, frequencies of accelerations and decelerations, and alerts ranged from 45% to 99% and were highest for baseline rate and signal loss and lowest for acceleration and deceleration counts. Interobserver agreement for alerts was relatively high (range, 72%-84%), with virtually no difference between any of the observers and the computer (range, 76.9%-79.2%; κ = 0.25). Conclusion: Use of the National Institute of Child Health and Human Development guidelines for visual fetal heart rate interpretation did not increase agreements on most fetal heart rate features beyond those expected by chance or noted in previous reports. These guidelines did appear to blunt some interpretive differences, possibly as a result of observer background. Although levels of agreement on fetal heart rate features differed, agreements on clinical alerts were similar among all observers and a computerized fetal heart rate monitoring system. Computer analysis of fetal heart rate tracings could eliminate interobserver variation that results from visual analysis and could produce more consistent clinical responses to normal and abnormal fetal heart rate patterns. (Am J Obstet Gynecol 2000;183:361-6.)

Statistical models of outcome in malpractice lawsuits involving death or neurologically impaired infants

The objective was to determine whether factors could be identified in medical and legal records that are associated with the successful defense of obstetrical malpractice cases involving the death or neurological impairment of infants. Obstetrical claims (169) closed by PROMUTUAL between January 1, 1990, and December 31, 1994, were retrospectively abstracted and analyzed to identify associations between medical and legal factors, and the medicolegal outcome. Multivariable analysis identifies that the use of pitocin, diagnosis of asphyxia, a delay in delivery, and the use of multiple defense expert witnesses decreased the chances of a successful defense. Two statistical models explaining indemnity payment were developed. The first, based on medical outcome, showed an increased indemnity payment when a case involved major neurological deficits, diagnosis of asphyxia, newborn seizures, later year of delivery, and participation of a particular defense firm. Perinatal or childhood death and the use of pitocin were indicators of a decrease in payment. The second model was based on long-term care requirements. In this model, indicators of increased indemnity payment were: nonreassuring intrapartum fetal heart rate tracing, later year of delivery, intensity of long-term care required, and participation of a particular defense law firm. Perinatal or childhood death, the use of pitocin, and settlement date increasingly removed from the occurrence date were the determinants of decreased payments in this model. Finally, the presence of major neurological deficits, the prolongation of a case, and the involvement of multiple law firms and defense witnesses increased the expense charged to and paid by the insurance company. Using the medical, legal, and financial data relevant to 169 obstetrical cases closed by one malpractice insurance carrier between 1990 and 1994, statistical models with potential predictive values for future malpractice claims involving neurologically impaired infants were constructed. These models may help determine in advance the chance a future case has for successful defense and the likely amount of expense and indemnity dollars that will be paid out to settle and defend it.

Effects of Narcotic and Non-Narcotic Continuous Epidural Anesthesia on Intrapartum Fetal Heart Rate Tracings as Measured by Computer Analysis

Effects of Narcotic and Non-Narcotic Continuous Epidural Anesthesia on Intrapartum Fetal Heart Rate Tracings as Measured by Computer Analysis

Comparison of the effects of meperidine and nalbuphine on intrapartum fetal heart rate tracings

To examine the effects of meperidine and nalbuphine on intrapartum fetal heart rate (FHR) tracings using computer analysis. We studied 28 women with uncomplicated pregnancies in early labor at term with reactive FHR tracings. The women were randomized to receive either meperidine 50 mg or nalbuphine 10 mg intravenously on request. One-hour FHR recordings were obtained before and immediately after administration of the medications. There were no significant differences in the FHR characteristics of the two groups during the pre-treatment period. Nalbuphine significantly decreased the number of accelerations of 10 beats per minute (17 versus 4, P = .003) and 15 beats per minute (10 versus 1.5, P = .001), time spent in episodes of high variation (35.5 versus 10 minutes, P = .004), long-term variation (47 versus 29.8 milliseconds, P = .002), and short-term variation (8.4 versus 6.4 milliseconds, P = .03). Meperidine had no significant effect on any FHR characteristic. In the early intrapartum period of normal term pregnancies and at commonly used dosages, nalbuphine had a significant effect on FHR tracings, whereas meperidine had no effect, as determined by computer analysis.

Vibroacoustic Stimulation for Risk Assessment

VAS of the human fetus produces a profound alteration of fetal behavior and FHR. Many authors have reported on the success of the technique in improving the efficiency of antepartum FHR testing without altering the predictive reliability of the tests. VAS has other potential advantages in the antepartum assessment of fetal well-being and provocation of fetal activity to improve ultrasonographic anatomic visualization. Experimentally, VAS offers a unique opportunity to assess how the fetus responds to its external environment. The information currently available suggests that exposure of the fetus to VAS is safe in its present clinical applications. Additional investigation is needed to characterize the best frequency, duration, intensity, and choice of stimulus to provide the most consistent responses. The literature to date presents a confusing array of studies that have used different methodologies, making comparisons of studies difficult. It is the opinion of the author that VAS is a safe clinical technique as currently employed.

The predictive value of intrapartum fetal heart rate abnormalities in the extremely premature infant

Our purpose was to evaluate the validity of intrapartum fetal heart rate tracings in predicting short- and long-term outcomes of infants delivered between 24 and 26 weeks. Fetal heart rate tracings obtained during the last hour before delivery of fetuses delivered at 24 to 26 weeks' gestation were reviewed. Two perinatologists blinded to neonatal outcome evaluated the tracings for the following attributes: baseline rate and variability, presence and severity of decelerations, and overall impression (reassuring, nonreassuring, or ominous). Measured outcomes were cord blood pH; Apgar scores; intraventricular hemorrhage; duration of assisted ventilation; and hospitalization, survival, and developmental status at 1 year. The fetal heart rate attribute that was found to be predictive of neonatal outcome was the presence of any bradycardia or tachycardia found in any 10-minute window (designated "baseline rate abnormality"). This correlated with neonatal death (p < 0.007). None of the other fetal heart rate attributes were associated with any neonatal outcome. Intraobserver agreement was "fair to good" (kappa 0.5). Fetal baseline rate abnormalities (either tachycardia or bradycardia) were predictive of neonatal death in extremely premature fetuses.

The umbilical coiling index

Our purpose was to objectively quantitate umbilical vascular coiling. In this prospective study the umbilical cords and delivery records of 100 consecutive liveborn neonates were studied. The umbilical coiling index of each cord was determined by dividing the total number of complete umbilical vascular coils by the umbilical cord length (in centimeters). The obstetric history, intrapartum fetal heart rate tracing, and pregnancy outcome of each fetus were evaluated without knowledge of the umbilical coiling index. The mean umbilical coiling index was 0.21 +/- 0.07 (SD) coils per centimeter. The 100 values were normally distributed. Among those whose umbilical coiling index values fell < or = 10th percentile, there was a significantly greater incidence of karyotypic abnormalities (p = 0.04), meconium staining (p = 0.03), and operative intervention for fetal distress (p = 0.03). There was a significantly greater incidence of moderate or severe variable fetal heart rate decelerations for those whose umbilical coiling index value was either < or = 10th percentile (0.1 coils per centimeter) or > 90th percentile (0.3 coils per centimeter) (p = 0.03). The umbilical coiling index may have utility for objectively describing the degree of umbilical vascular coiling.

The umbilical coiling index

OBJECTIVE: Our purpose was to objectively quantitate umbilical vascular coiling. STUDY DESIGN: In this prospective study the umbilical cords and delivery records of 100 consecutive liveborn neonates were studied. The umbilical coiling index of each cord was determined by dividing the total number of complete umbilical vascular coils by the umbilical cord length (in centimeters). The obstetric history, intrapartum fetal heart rate tracing, and pregnancy outcome of each fetus were evaluated without knowledge of the umbilical coiling index. RESULTS: The mean umbilical coiling index was 0.21 ± 0.07 (SD) coils per centimeter. The 100 values were normally distributed. Among those whose umbilical coiling index values fell ≤10th percentile, there was a significantly greater incidence of karyotypic abnormalities (p = 0.04), meconium staining (p = 0.03), and operative intervention for fetal distress (p = 0.03). There was a significantly greater incidence of moderate or severe variable fetal heart rate decelerations for those whose umbilical coiling index value was either ≤10th percentile (0.1 coils per centimeter) or >90th percentile (0.3 coils per centimeter) (p = 0.03). CONCLUSION: The umbilical coiling index may have utility for objectively describing the degree of umbilical vascular coiling. (AM J OBSTET GYNECOL 1994;170:29-32.)

The use of fetal echocardiography for predicting intrapartum fetal heart rate patterns in the post-term pregnancy.

One of the shortcomings of antepartum testing in the post-term pregnancy is that it does not identify the majority of fetuses who develop abnormal intrapartum fetal heart rate changes. The purpose of this study was to determine whether antenatal cardiovascular evaluation could aid in the identification of post-term fetuses at risk for intrapartum heart rate abnormalities. Seventy-five patients with a gestational age greater than 41 weeks underwent a non-stress test, amniotic fluid index and real-time assessment of the heart for the presence or absence of a pericardial effusion. M-mode measurements of the right ventricular inner dimension (RVID), left ventricular inner dimension (LVID), biventricular outer dimension (BVOD) and Doppler velocimetry of the umbilical artery (S/D) were performed. Group I (n = 32) had normal intrapartum heart rate tracings. Group II (n = 20) had abnormal intrapartum fetal heart rate tracings but did not undergo emergency delivery. Group III (n = 23) had abnormal intrapartum fetal heart rate tracings but underwent emergency delivery. When comparing Group I with Group II, the latter had significant differences for abnormal RVID, RVID/LVID ratio, and pericardial effusion. When comparing Groups I and III, there were significant differences for RVID, RVID/LVID ratio, pericardial effusion, BVOD, LVID and amniotic fluid index. Neither the non-stress test nor S/D predicted abnormal intrapartum fetal heart rate patterns. For prediction of abnormal intrapartum heart rate patterns, the sensitivities of the RVID (0.79), LVID (0.33), RVID/LVID ratio (0.72) and BVOD (0.63) were 1.7-4 times greater than the non-stress test (0.19) and the sensitivities of the RVID, RVID/LVID ratio and BVOD were 2 times greater than the amniotic fluid index (0.28). The positive (0.50-0.86) and negative (0.42-0.68) predictive values were similar for all groups. To predict emergency delivery associated with abnormal heart rate tracings, the sensitivities of the RVID (0.83), RVID/LVID ratio (0.70) and BVOD (0.65) were 2.5-3 times greater than the non-stress test (0.26) and 1.5 times greater than the amniotic fluid index (0.39). The positive (0.36-0.56) and negative (0.70-0.86) predictive values were similar. The presence of pericardial effusion had a higher sensitivity than the non-stress test and amniotic fluid index for predicting abnormal intrapartum heart rate patterns but not emergency delivery. Doppler velocimetry of the umbilical artery had a lower sensitivity than the non-stress test and amniotic fluid index for predicting intrapartum heart rate patterns as well as identifying the fetus needing emergency delivery. The results of this study would suggest that there is initially dilatation of the right ventricle which may be associated with abnormal intrapartum fetal heart rate patterns. However, when the left ventricle dilates, leading to cardiomegaly, there is a greater incidence of abnormal intrapartum fetal heart rate changes and associated emergency delivery. The amniotic fluid index appears to be a later finding for predicting abnormal intrapartum fetal heart rate changes.

Stuck Twin with Cotwin Nonimmune Hydrops: Successful Treatment by Amniocentesis

Until the recent introduction of therapeutic amniocentesis, pregnancies complicated by the stuck twin phenomenon usually suffered poor outcomes. We report the first case in which a single amniocentesis of the cotwin was followed by equalization of amniotic fluid volume in both sacs, resolution of nonimmune hydrops in the cotwin, and delivery of 2 healthy infants. The cause of the phenomenon in this was most likely severe twin-twin transfusion, based on a negative hematologic and serologic immune and nonimmune hydrops evaluation, and placental histology revealing a superficial large-caliber arteriovenous anastomosis joining the twins' circulations without an intervening capillary bed. The mechanism proposed for the physiologic response in this case to therapeutic amniocentesis is based on the correction of abnormal amniotic fluid volumes and pressures. This contention is supported by histologic evaluation of the placenta and the intrapartum fetal heart rate tracing.

Heart Rate Cyclicity During Labor in Healthy Term Fetuses

Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, University of Connecticut Health Center, Farmington, Connecticut

Heart rate cyclicity during labor in healthy term fetuses.

Fifty-four intrapartum fetal heart rate (FHR) tracing were subjected to retrospective analysis of the presence, length, and frequency of cyclic changes in long-term variability (cyclicity). All patients had spontaneous uncomplicated labor and received no narcotics or analgesics. The following cycles were identified according the difference in long-term variability in terms of amplitude range: cycle A, 0 to 2.5 beats/min; cycle B, 3 to 5 beats/min; cycle C, 6 to 10 beats/min; and cycle D, 11 to 20 beats/min. The frequency and length of FHR cycles was established in the latent, active phases and second stage of labor. Periods of diminished variability should be followed by fetal acid-base assessment only if their duration exceeds the established norms.

Telephone transmission of fetal heart rate monitor data: The experience at the University of Connecticut Health Center

This report reviews the experience at the University of Connecticut Health Center using the Fetal Assessment Consultative Transmission Service (FACTS) system during a 212-year period. This system, which permits direct transmission of antepartum and/or intrapartum fetal heart rate tracings via a telephone line, allows the obstetric staffs of smalier community hospitals to obtain an immediate consultation from the University of Connecticut Health Center on a 24 hour per day basis. A total of 511 fetal heart rate tracings were analyzed. Two hundred forty-five were intrapartum, 206 antepartum, and 60 were transmitted for educational purposes. The results indicate an imperative need for such a service from a tertiary care center to improve the quality of regional perinatal care and to determine the future direction of the regional educational program for physicians and nurses.

The influence of observer-dependent properties upon the evaluation of fetal heart rate recordings (author's transl)

The significance of the observer's experience in the evaluation of fetal heart rate (FHR) recordings has not yet been dealt with in the literature. Therefore the qualitative and quantitative determination of these subjective factors has been studied as follows at the University of Basle Department of Obstetrics and Gynecology: Twenty FHR recordings were simultaneously analyzed by twenty-five residents with different levels of obstetrical experience. The results were compared with those of physicians with expertise in FHR monitoring. It became obvious that ominous antepartum FHR tracings were significantly less often correctly identified than harmful intrapartum recordings (p less than 0.001). Harmless changes in intrapartum FHR tracings were more frequently misjudged as being ominous than normal antepartum FHR tracings (p less than 0.05). The following conclusions were made: - There is a real danger of a fatal error in the interpretation of ominous antepartum FHR recordings. - The presented data seem to reveal the source of the increased caesarean section rate described by others as to be associated with FHR monitoring. - The errors in the interpretation of FHR tracings decrease significantly (p less than 0.05) with increasing experience. Thus physicians' education is eminently important for the correct use of electronic fetal monitoring.

Intrapartum fetal heart rate and sudden infant death syndrome

The intrapartum fetal heart rate (FHR) tracings of 20 infants who died of sudden infant death syndrome (SIDS) and 20 matched control infants, both drawn from a population at increased obstetrical risk, were compared. This is a blind retrospective study aimed at quantifying (a) the incidence of FHR patterns, (b) the range of FHR and variability levels, and (c) the episodes of variable and late decelerations occurring in conjunction with abnormal FHR levels. Tracings of SIDS infants were similar to those of control infants. Although the three infants with bradycardic FHR levels were restricted to the SIDS group, infants in this group could not be reliably differentiated from control infants on the basis of intrapartum FHR tracings.