The conduction velocity and propagation patterns of the electrohysterogram (EHG) provide fundamental information on the electrophysiological condition of the uterus. However, the accuracy of these ...measurements can be impaired by both the poor spatial selectivity and sensitivity to the relative direction of the contraction propagation associated with conventional disc electrodes. Concentric ring electrodes could overcome these limitations. The aim of this study was to examine the feasibility of picking up surface EHG signals using a new flexible tripolar concentric ring electrode (TCRE), and to compare these signals with conventional bipolar recordings. Simultaneous recording of conventional bipolar signals and bipolar concentric EHG (BC-EHG) were carried out on 22 pregnant women. Signal bursts were characterized and compared. No significant differences were found between the channels in either duration or dominant frequency in the Fast Wave High frequency range. Nonetheless, the high pass filtering effect of the BC-EHG recordings gave lower frequency content between 0.1 and 0.2 Hz. Although the BC-EHG signal amplitude was about 5–7 times smaller than that of bipolar recordings, a similar signal-to-noise ratio was obtained. These results suggest that the flexible TCRE is able to pick up uterine electrical activity and could provide additional information for deducing the uterine electrophysiological condition.
Objective: Preterm birth is a large-scale clinical problem involving over 10% of infants. Diagnostic means for timely risk assessment are lacking and the underlying physiological mechanisms unclear. ...To improve the evaluation of pregnancy before term, we introduce dedicated entropy measures derived from a single-channel electrohysterogram (EHG). Methods: The estimation of approximate entropy (ApEn) and sample entropy (SampEn) is adjusted to monitor variations in the regularity of single-channel EHG recordings, reflecting myoelectrical changes due to pregnancy progression. In particular, modifications in the tolerance metrics are introduced for improving robustness to EHG amplitude fluctuations. An extensive database of 58 EHG recordings with 4 monopolar channels in women presenting with preterm contractions was manually annotated and used for validation. The methods were tested for their ability to recognize the onset of labor and the risk of preterm birth. Comparison with the best single-channel methods according to the literature was performed. Results: The reference methods were outperformed. SampEn and ApEn produced the best prediction of delivery, although only one channel showed a significant difference (p <;0.04) between labor and nonlabor. The modified ApEn produced the best prediction of preterm delivery, showing statistical significance (p <;0.02) in three channels. These results were also confirmed by the area under the receiver operating characteristic curve and fivefold cross validation. Conclusion: The use of dedicated entropy estimators improves the diagnostic value of EHG analysis earlier in pregnancy. Significance: Our results suggest that changes in the EHG might manifest early in pregnancy, providing relevant prognostic opportunities for pregnancy monitoring by a practical single-channel solution.
Uterine contraction (UC) is an important clinical indictor for monitoring uterine activity. The purpose of this study is to develop a portable electrohysterogram (EHG) recording system (called ...PregCare) for monitoring UCs with EHG signals. The PregCare consisted of sensors, a signal acquisition device, and a computer with application software. Eight-channel EHG signals, the tocodynamometry (TOCO) signal, and maternal perception were recorded simultaneously by the signal acquisition device controlled by the computer via Bluetooth. PregCare was firstly evaluated by a signal simulator. Its relative error (RE) and coefficient of variation (CV) were calculated, and its agreement with the commercial instrument PowerLab was assessed by Bland–Altman plots. After that, PregCare was applied to 20 pregnant women in a hospital to record their EHG signals. These EHG signals were preprocessed and segmented into UCs and non-UCs. Then, the EHG features corresponding to UCs and non-UCs were extracted, respectively, including power spectral density (PSD), root mean square (RMS), peak frequency (PF), median frequency (MDF), and sample entropy (SamEn). One-way ANOVA was employed to assess the difference between UCs and non-UCs. The results show that RE and CV were less than 8% and 0.03%, respectively, which indicated the high accuracy and repeatability of PregCare. The small differences of mean and standard deviation indicated the high agreement between PregCare and PowerLab. Besides, the PSD of UCs was much larger than non-UCs between 0 and 0.7 Hz. RMS of UCs was significantly larger than non-UCs (p<0.05). PF and SamEn of UCs were significantly smaller than non-UCs (p<0.05). In conclusion, the developed EHG recording system was able to record EHG signals reliably. It has the advantages of portability, low power consumption, and wireless transmission, which can be used for long-term monitoring of UCs and prediction of the preterm delivery.
The serial fetal monitoring recommended for women with high-risk pregnancies places a substantial burden on the patient, often disproportionately affecting underprivileged and rural populations. A ...telehealth solution that can empower pregnant women to obtain recommended fetal surveillance from the comfort of their own home has the potential to promote health equity and improve outcomes. We have previously validated a novel, wireless pregnancy monitor that can remotely capture fetal and maternal heart rates. However, such a device must also detect uterine contractions if it is to be used to robustly conduct remote nonstress tests.
This study aimed to describe and validate a novel algorithm that uses biopotential and acoustic signals to noninvasively detect uterine contractions via a wireless pregnancy monitor.
A prospective, open-label, 2-center study evaluated simultaneous detection of uterine contractions by the wireless pregnancy monitor and an intrauterine pressure catheter in women carrying singleton pregnancies at ≥32 0/7 weeks’ gestation who were in the first stage of labor (ClinicalTrials.gov Identifier: NCT03889405). The study consisted of a training phase and a validation phase. Simultaneous recordings from each device were passively acquired for 30 to 60 minutes. In a subset of the monitoring sessions in the validation phase, tocodynamometry was also deployed. Three maternal-fetal medicine specialists, blinded to the data source, identified and marked contractions in all modalities. The positive agreement and false-positive rates of both the wireless monitor and tocodynamometry were calculated and compared with that of the intrauterine pressure catheter.
A total of 118 participants were included, 40 in the training phase and 78 in the validation phase (of which 39 of 78 participants were monitored simultaneously by all 3 devices) at a mean gestational age of 38.6 weeks. In the training phase, the positive agreement for the wireless monitor was 88.4% (1440 of 1692 contractions), with a false-positive rate of 15.3% (260/1700). In the validation phase, using the refined and finalized algorithm, the positive agreement for the wireless pregnancy monitor was 84.8% (2722/3210), with a false-positive rate of 24.8% (897/3619). For the subgroup who were monitored only with the wireless monitor and intrauterine pressure catheter, the positive agreement was 89.0% (1191/1338), with a similar false-positive rate of 25.4% (406/1597). For the subgroup monitored by all 3 devices, the positive agreement for the wireless monitor was significantly better than for tocodynamometry (P<.0001), whereas the false-positive rate was significantly higher (P<.0001). Unlike tocodynamometry, whose positive agreement was significantly reduced in the group with obesity compared with the group with normal weight (P=.024), the positive agreement of the wireless monitor did not vary across the body mass index groups.
This novel method to noninvasively monitor uterine activity, via a wireless pregnancy monitoring device designed for self-administration at home, was more accurate than the commonly used tocodynamometry and unaffected by body mass index. Together with the previously reported remote fetal heart rate monitoring capabilities, this added ability to detect uterine contractions has created a complete telehealth solution for remote administration of nonstress tests.
To reduce the morbidity and mortality associated with preterm birth, home uterine activity monitoring aims for early detection of increased contraction frequency, and early intervention with ...tocolytic drugs to inhibit labour and prolong pregnancy. However, the effectiveness of such monitoring is disputed.
To determine whether home uterine activity monitoring is effective in improving the outcomes for women and their infants considered to be at high risk of preterm birth, when compared with conventional or other care packages that do not include home uterine monitoring.
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2014), CENTRAL (The Cochrane Library 2014, Issue 8), MEDLINE (1966 to 31 August 2014), EMBASE (1974 to 31 August 2014), CINAHL (1982 to 31 August 2014) and scanned reference lists of retrieved studies.
Randomised control trials of home uterine activity monitoring, with or without patient education programmes, for women at risk for preterm birth, in comparison to the same care package without home uterine activity monitoring.
Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We did not attempt to contact authors to resolve queries.
There were 15 included studies (total number of enrolled participants 6008); 13 studies contributed data. Women using home uterine monitoring were less likely to experience preterm birth at less than 34 weeks (risk ratio (RR) 0.78; 95% confidence interval (CI) 0.62 to 0.99; three studies, n = 1596; fixed-effect analysis) (GRADE high). The significant difference was not evident when we carried out a sensitivity analysis, restricting the analysis to studies at low risk of bias based on study quality (RR 0.75; 95% CI 0.57 to 1.00, one study, 1292 women). There was no significant difference in the rate of perinatal mortality (RR 1.22; 95% CI 0.86 to 1.72; two studies, n = 2589) (GRADE low)There was no significant difference in the number of preterm births at less than 37 weeks (average RR 0.85; CI 0.72 to 1.01; eight studies, n = 4834; random-effects, T² = 0.03, I² = 68%) (GRADE very low). Infants born to women using home uterine monitoring were less likely to be admitted to neonatal intensive care unit (average RR 0.77; 95% CI 0.62 to 0.96; five studies, n = 2367; random-effects, T² = 0.02, I² = 32%) (GRADE moderate). The difference was not statistically significant when only high quality studies were included (RR 0.86; 95% CI 0.74 to 1.01; one study, n = 1292). Women using home uterine monitoring made more unscheduled antenatal visits (mean difference (MD) 0.49; 95% CI 0.39 to 0.62; two studies, n = 3707) (GRADE moderate). Women using home uterine monitoring were also more likely to have prophylactic tocolytic drug therapy (average RR 1.21; 95% CI 1.01 to 1.45; seven studies, n = 4316; random-effects. T² = 0.03, I² = 62%) but this difference was no longer significant when the analysis was restricted to higher quality studies (average RR 1.22; 95% CI 0.90 to 1.65, three studies, n = 3749,random-effects, T² = 0.05, I² = 76%) (GRADE low). One small study reported that the home uterine monitoring group spent fewer days in hospital antenatally. No data on maternal anxiety or acceptability were found.
Home uterine monitoring may result in fewer admissions to a neonatal intensive care unit but more unscheduled antenatal visits and tocolytic treatment, but the level of evidence is generally low to moderate. Important group differences were not evident when sensitivity analysis was undertaken using only high quality trials. There is no impact on maternal and perinatal outcomes such as perinatal mortality or incidence of preterm birth.
Objective Power spectrum (PS) of uterine electromyography (EMG) can identify true labor. EMG propagation velocity (PV) to diagnose labor has not been reported. The objective was to compare uterine ...EMG against current methods to predict preterm delivery. Study Design EMG was recorded in 116 patients (preterm labor, n = 20; preterm nonlabor, n = 68; term labor, n = 22; term nonlabor, n = 6). A Student t test was used to compare EMG values for labor vs nonlabor ( P < .05, significant). Predictive values of EMG, Bishop score, contractions on tocogram, and transvaginal cervical length were calculated using receiver-operator characteristics analysis. Results PV was higher in preterm and term labor compared with nonlabor ( P < .001). Combined PV and PS peak frequency predicted preterm delivery within 7 days with area under the curve (AUC) of 0.96. Bishop score, contractions, and cervical length had an AUC of 0.72, 0.67, and 0.54. Conclusion Uterine EMG PV and PS peak frequency more accurately identify true preterm labor than clinical methods.
It has been hypothesized that internal tocodynamometry, as compared with external monitoring, may provide a more accurate assessment of contractions and thus improve the ability to adjust the dose of ...oxytocin effectively, resulting in fewer operative deliveries and less fetal distress. However, few data are available to test this hypothesis.
We performed a randomized, controlled trial in six hospitals in The Netherlands to compare internal tocodynamometry with external monitoring of uterine activity in women for whom induced or augmented labor was required. The primary outcome was the rate of operative deliveries, including both cesarean sections and instrumented vaginal deliveries. Secondary outcomes included the use of antibiotics during labor, time from randomization to delivery, and adverse neonatal outcomes (defined as any of the following: an Apgar score at 5 minutes of less than 7, umbilical-artery pH of less than 7.05, and neonatal hospital stay of longer than 48 hours).
We randomly assigned 1456 women to either internal tocodynamometry (734) or external monitoring (722). The operative-delivery rate was 31.3% in the internal-tocodynamometry group and 29.6% in the external-monitoring group (relative risk with internal monitoring, 1.1; 95% confidence interval CI, 0.91 to 1.2). Secondary outcomes did not differ significantly between the two groups. The rate of adverse neonatal outcomes was 14.3% with internal monitoring and 15.0% with external monitoring (relative risk, 0.95; 95% CI, 0.74 to 1.2). No serious adverse events associated with use of the intrauterine pressure catheter were reported.
Internal tocodynamometry during induced or augmented labor, as compared with external monitoring, did not significantly reduce the rate of operative deliveries or of adverse neonatal outcomes. (Current Controlled Trials number, ISRCTN13667534; Netherlands Trial number, NTR285.)
Real-time electrohysterography (EHG)-based technologies have recently become available for uterine monitoring during term labor. Therefore, obstetricians need to be familiar with the diagnostic ...value, advantages, and limitations of using EHG.
The aims of this study were to determine the diagnostic value of EHG in comparison to (1) the intrauterine pressure catheter (IUPC), (2) the external tocodynamometer (TOCO), and (3) in case of maternal obesity; (4) to evaluate EHG from users' and patients' perspectives; and (5) to assess whether EHG can predict labor outcome.
A systematic review was performed in the MEDLINE, EMBASE, and Cochrane library in October 2017 resulting in 209 eligible records, of which 20 were included.
A high sensitivity for contraction detection was achieved by EHG (range, 86.0%-98.0%), which was significantly better than TOCO (range, 46.0%-73.6%). Electrohysterography also enhanced external monitoring in case of maternal obesity. The contraction frequency detected by EHG was on average 0.3 to 0.9 per 10 minutes higher compared with IUPC, which resulted in a positive predictive value of 78.7% to 92.0%. When comparing EHG tocograms with IUPC traces, an underestimation of the amplitude existed despite that patient-specific EHG amplitudes have been mitigated by amplitude normalization. Obstetricians evaluated EHG tocograms as better interpretable and more adequate than TOCO. Finally, potential EHG parameters that could predict a vaginal delivery were a predominant fundal direction and a lower peak frequency.
Electrohysterography enhances external uterine monitoring of both nonobese and obese women. Obstetricians consider EHG as better interpretable; however, they need to be aware of the higher contraction frequency detected by EHG and of the amplitude mismatch with intrauterine pressure measurements.
Introduction
Fetal electrocardiography (NI‐fECG) and electrohysterography (EHG) have been proven more accurate and reliable than conventional non‐invasive methods (doppler ultrasound and ...tocodynamometry) and are less affected by maternal obesity. It is still unknown whether NI‐fECG and EHG will eliminate the need for invasive methods, such as the intrauterine pressure catheter and fetal scalp electrode. We studied whether NI‐fECG and EHG can be successfully used during labor.
Material and Methods
A prospective clinical pilot study was performed in a tertiary care teaching hospital. A total of 50 women were included with a singleton pregnancy with a gestational age between 36+0 and 42+0 weeks and had an indication for continuous intrapartum monitoring. The primary study outcome was the percentage of women with NI‐fECG and EHG monitoring throughout the whole delivery. Secondary study outcomes were reason and timing of a switch to conventional monitoring methods (i.e., tocodynamometry and fetal scalp electrode or doppler ultrasound), repositioning of the abdominal electrode patch, success rates (i.e., the percentage of time with signal output), and obstetric and neonatal outcomes. Clinical trial registration: Dutch trial register (NL8024).
Results
In 45 women (90%), NI‐fECG and EHG monitoring was used throughout the whole delivery. In the other five women (10%), there was a switch to conventional methods: in two women because of insufficient registration quality of uterine contractions and in three women because of insufficient registration quality of the fetal heart rate. In three out of five cases, the switch was after full dilation was reached. Repositioning of the abdominal electrode patch occurred in two women. The overall success rate was 94.5%. In 16% (n = 8) of women, a cesarean delivery was performed due to non‐progressing dilation (n = 7) and due to suspicion of fetal distress (n = 1). Neonatal metabolic acidosis did not occur. Two neonates (4%) were admitted to the neonatal intensive care unit for complications not related to intrapartum monitoring.
Conclusions
NI‐fECG and EHG can be successfully used during labor in 90% of women. Future research is needed to conclude whether implementation of electrophysiological monitoring can improve obstetric and neonatal outcomes.
NI‐fECG and EHG outperform conventional non‐invasive methods (i.e., DU and TOCO), and are not accompanied by the disadvantages of invasive methods (i.e., FSE and IUPC). NI‐fECG and EHG monitoring was successful in 90% of women, with a high success rate.
The objective of this study was to determine the performance of biophysical and biochemical tests for the prediction of preterm birth in both asymptomatic and symptomatic women with twin gestations. ...We identified a total of 19 tests proposed to predict preterm birth, mainly in asymptomatic women. In these women, a single measurement of cervical length with transvaginal ultrasound before 25 weeks of gestation appears to be a good test to predict preterm birth. Its clinical potential is enhanced by the evidence that vaginal progesterone administration in asymptomatic women with twin gestations and a short cervix reduces neonatal morbidity and mortality associated with spontaneous preterm delivery. Other tests proposed for the early identification of asymptomatic women at increased risk of preterm birth showed minimal to moderate predictive accuracy. None of the tests evaluated in this review meet the criteria to be considered clinically useful to predict preterm birth among patients with an episode of preterm labor. However, a negative cervicovaginal fetal fibronectin test could be useful in identifying women who are not at risk for delivering within the next week, which could avoid unnecessary hospitalization and treatment. This review underscores the need to develop accurate tests for predicting preterm birth in twin gestations. Moreover, the use of interventions in these patients based on test results should be associated with the improvement of perinatal outcomes.
PDF
