Comparison of visual and computerized interpretation of nonstress test results in a randomized controlled trial. Screening for fetal well-being in a high-risk pregnant population comparing the nonstress test with umbilical artery Doppler velocimetry: a randomized controlled clinical trial. Fetal acoustic stimulation testing. II. A randomized clinical comparison with the nonstress test. Comparison of the acoustic stimulation test with nonstress test. A randomized, controlled clinical trial. Vibroacoustic stimulation and fetal heart rate in nonstress tests. Fetal biophysical profile score and the nonstress test: a comparative trial. The effect of introduction of umbilical Doppler recordings to obstetric practice. Effect of vibratory acoustic stimulation on the duration of fetal heart rate monitoring tests.
This study tested the null hypothesis that the number of fetal surveillance tests and perinatal outcomes would not differ statistically between pregnancies randomized to visual or computerized interpretation of antepartum nonstress test results.
                A prospective, randomized controlled trial was conducted, which required a sample size of 404 patients. By using a random-number table with assignment codes concealed in opaque envelopes, half of the patients were randomized to computerized interpretation of nonstress test results and half to standard visual interpretation of nonstress test results. The amount of antepartum testing and the perinatal outcome were measured and compared between the groups. Logistic regression analysis was used to control for maternal risk factors while morbidity differences between the 2 groups were assessed.
                The 2 randomized groups were similar at baseline, but the computerized interpretation group had significantly fewer biophysical profiles compared with the visual interpretation group (1.3 +/- 1.8 vs 1.9 +/- 2.1; P =.002). The patients in the computerized interpretation group spent less time per test than patients in the visual interpretation group (12 vs 20 minutes; P =.038). After the 5 pregnancies with congenital anomalies were excluded, the overall perinatal outcome was similar in the 2 groups. The computerized interpretation group, however, had a slightly lower proportion of infants who required >/=2 days of neonatal intensive care (7.4% vs 12.4%; P =.086; odds ratio, 0.56; 95% confidence interval, 0.29-1.09). The average number of neonatal intensive care days was also slightly lower in the computerized interpretation group (0.4 vs 0.9; P =.105). Neither of these variables was statistically significant.
                Computerized interpretation of nonstress test results is associated with fewer additional fetal surveillance examinations, less time spent in testing, and a similar length of stay in the neonatal intensive care unit compared with standard visual interpretation. The purpose of this study was to evaluate the ability of two different modes of antepartum fetal testing to screen for the presence of peripartum morbidity, as measured by the cesarean delivery rate for fetal distress in labor.
                Over a 36-month period, all patients who were referred to the Fetal Assessment Unit at BC Women's Hospital because of a perceived increased fetal antepartum risk at a gestational age of > or =32 weeks of gestation were approached to participate in this study. Fetal surveillance of these women was allocated randomly to either umbilical artery Doppler ultrasound testing or nonstress testing as a screening test for fetal well-being. If either the umbilical artery Doppler testing or the nonstress testing was normal, patients were screened subsequently with the same technique, according to study protocol. When the Doppler study showed a systolic/diastolic ratio of >90th percentile or the nonstress testing was equivocal (ie, variable decelerations), an amniotic fluid index was performed, as an additional screening test. When the amniotic fluid index was abnormal (<5th percentile), induction and delivery were recommended. When the Doppler study showed absent or reversed diastolic blood flow or when the nonstress test result was abnormal, induction and delivery were recommended to the attending physician. Statistical comparisons between groups were performed with an unpaired t test for normally distributed continuous variables and chi(2) test for categoric variables.
                One thousand three hundred sixty patients were assigned randomly to groups in the study; 16 patients were lost to follow up. Six hundred forty-nine patients received Doppler testing and 691 received nonstress testing. The mean number of visits for the Doppler test and nonstress test groups was two versus two, respectively. The major indications for fetal assessment included postdates (43%), decreased fetal movement (22%), diabetes mellitus (11%), hypertension (10%), and intrauterine growth restriction (7%). The incidence of cesarean delivery for fetal distress was significantly lower in the Doppler group compared with the nonstress testing group (30 [4.6%] vs 60 [8.7%], respectively; P <.006). The greatest impact on the reduction in cesarean deliveries for fetal distress was seen in the subgroups in which the indication for testing was hypertension and suspected intrauterine growth restriction.
                Umbilical artery Doppler as a screening test for fetal well-being in a high-risk population was associated with a decreased incidence of cesarean delivery for fetal distress compared to the nonstress testing, with no increase in neonatal morbidity. Antepartum fetal heart rate testing, specifically the nonstress test, is of accepted value in the antenatal surveillance of high-risk pregnancies. Fetal rest-activity cycles coupled with arbitrary test intervals appear to lead to falsely nonreactive tests. Methods to alter fetal behavioral states have not been uniformly successful. A retrospective analysis of the adjunctive use of acoustic stimulation at our institution demonstrated a 50% reduction in the number of nonreactive tests. Consequently a prospective randomized clinical trial was undertaken to compare the standard nonstress test with the fetal acoustic stimulation test. Those patients randomized to the fetal acoustic stimulation test underwent transabdominal acoustic stimulation with a Model 5C electronic artificial larynx. The incidence of nonreactive tests was 14% in the control group and 9% in the study group (chi 2 = 11.09, p = 0.004). A significant reduction in testing time was also observed. The fetal acoustic stimulation test offers advantages over the traditional nonstress test by lowering the incidence of nonreactive tests and reducing testing time. The nonstress test (NST) is a helpful adjunct in the management of high-risk pregnancies. It has high predictability and a low false-negative rate but unfortunately has fairly high false-positive results. Attempts have been made to find a suitable stimulant to help decrease nonreactive results as well as to shorten the duration of testing: the recently introduced fetal acoustic stimulation test (AST) may have such attributes. This prospective, randomized clinical trial was carried out to assess the new test. A total of 1,300 individual tests were performed on high-risk pregnancies. Cases were randomized to receive either the AST or NST. All tracings were interpreted blindly by an independent perinatologist. The incidence of nonreactive tests was 6.8% in the AST group and 13.8% in the NST group (P < .001). There was a significant reduction in the time needed for a reactive test to occur. It can be concluded, therefore, that AST offers a greater advantage over NST by lowering both the incidence of nonreactive tests and testing time, thereby resulting in less of a need for the contraction stress test and biophysical profile. Two methods of vibroacoustic stimulation were compared with traditional nonstress tests. Fetal heart rate tracings following stimulation had more accelerations and were of greater amplitude and duration than in the control group. The length of time required to obtain a reactive nonstress test was almost 15 minutes shorter when vibroacoustic stimulation was applied than when vibroacoustic stimulation was not used. Vibroacoustic stimulation elicited a heightened reactivity that persisted beyond the observation period in 30 of 45 (67%) of the experimental group subjects. In this prospective blind study, 735 patients with high-risk pregnancies referred for antepartum testing of fetal well-being were randomly assigned to either a fetal biophysical profile scoring (375 patients) or a nonstress testing scheme (360 patients). Management was based on the results of antepartum tests, but the method of testing used was not disclosed. Fetal biophysical profile scoring resulted in a significantly higher positive predictive value in regards to low Apgar scores. Sensitivity, specificity, and accuracy, although higher with fetal biophysical profile scoring, did not demonstrate significant differences when compared with the nonstress test. The negative predictive value between the two methods was similar. All major anomalies were detected during ultrasound scanning, whereas none of these anomalies were detected by heart rate testing alone. To assess the effect on obstetric practice of clinician access to umbilical artery Doppler ultrasound results.
                Randomised controlled trial.
                A large teaching hospital.
                Two thousand two hundred and eighty-nine pregnancies defined as being at risk by referral for Doppler or fetal monitoring.
                Continuous wave Doppler studies of umbilical artery. Results immediately available to clinicians.
                Fetal outcome: perinatal mortality, Apgar score and admission to the neonatal unit. Obstetric intervention: admission to hospital, induction of labour and caesarean section. Use of of fetal well being: cardiotocography, biophysical profile and ultrasound biometry.
                The treatment and control groups were comparable in age, parity, gestation at point of entry and risk features. There were no overall differences in perinatal outcome, obstetric intervention or use of fetal monitoring. Examination of a subset recruited only because of hypertension or suspected intrauterine growth retardation (n = 754) similarly showed no difference attributable to group randomisation. Comparison of only those pregnancies retrospectively defined as low risk and high risk showed more use of cardiotocography in the high risk group with access to Doppler (P = 0.007) but no difference in the low risk group.
                Doppler umbilical artery recording has been shown to perform well in prediction power of antenatal fetal compromise. What has been examined in this study is the response of clinicians to the test. The results suggest that obstetricians do not use the test to modify their risk assessment, and, therefore, the need for fetal monitoring in particular pregnancies. There is a real need for accumulation of information from very large data sets, particularly in the prediction power of Doppler for antenatal fetal compromise from apparently chronic utero-placental cause to guide use of monitoring resources. If simply added to existing fetal monitoring techniques in a hospital where these are widely used, then umbilical artery Doppler recordings may at present simply involve extra resources of staff and expenses, without benefit. The ability of vibratory acoustic stimulation to shorten the duration of antepartum fetal heart rate monitoring was investigated by a randomized controlled trial. Vibratory acoustic stimulation did not shorten the overall duration of testing. This failure to improve the performance of antepartum monitoring appeared to result from prolonged accelerations, which complicated one third of the tests in which vibratory acoustic stimulation was employed. Further investigation is warranted using less profound methods of fetal stimulation.
There are insufficient data from randomised trials to guide practice regarding the management of DFM. Based on the results of other systematic reviews of management strategies for women whose babies are thought to be at risk of compromise for various reasons, the following strategies show promise and may be prioritised for further research: Doppler ultrasound studies, computerised cardiotocography, and fetal arousal to facilitate cardiotocography.
For settings where electronic fetal assessment methods are not available, clinical fetal arousal tests should be investigated.