Outcomes After Internal Versus External Tocodynamometry for Monitoring Labor

Abstract

BackgroundIt 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. MethodsWe 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). ResultsWe randomly assigned 1456 women to either internal tocodynamometry (734) or external monitoring (722). The operative-delivery rate was 31.3% in the internaltocodynamometry 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. ConclusionsInternal 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.

Perils of the new labor management guidelines

“…Studies have demonstrated that the use of IUPTs had no advantage when compared to noninvasive means of assessing uterine contractility during labor. [72][73][74] In addition, IUPT readings may depend on patient position, or on their location within the uterus and, most importantly, they do not correlate well with progress in cervical dilatation 70,75 or with the need for cesarean delivery. 69 Normal progress in dilatation is achieved over a broad range of uterine activity, and the pattern of contractions may be as important as their strength.…”

Quantification of elasticity changes in the myometrium during labor using Supersonic Shear Imaging: A feasibility study

“…uterine activity. Nevertheless, unlike external monitoring [2,4,10,11,26,12], internal monitoring requires membrane rupture and it has not showed significant improvement on the outcome of difficult births, which is of major concern in obstetrics. Moreover, intra-amniotic pressure is only an indirect assessment of the uterine activity.…”

An Integrated Review of Uterine Activity Monitoring for Evaluating Labor Dystocia

“…Moreover, a high frequency of women had vaginal births with uterine activity less than 200 MVUs. 20,22 Importantly, an increased fallto-rise ratio was associated with increased incidence of cesarean birth. 15,17,18 Similarly, increased EMG power density spectrum peak frequency 10,13 and increased sample entropy of the EMG signal were associated with cesarean birth.…”

“…In the parent study, the same research group reported that titration of oxytocin augmentation to uterine activity greater than 200 MVUs did not reduce the incidence of cesarean birth or adverse neonatal outcomes compared with titration to 3 to 4 contractions per 10 minutes measured by tocodynamometry. 22 In summary, lower MVU values are associated with cesarean birth; however, because of low predictive value for cesarean birth and high frequency of women with MVUs less than 200 who have a vaginal birth, uterine activity less than 200 MVUs may not be an appropriate criterion for the diagnosis of labor dystocia. Intrauterine pressure measured at single time points is not likely to identify uterine fatigue specifically as intrauterine pressure is expected to be reduced in both fatigue and understimulation of uterine contractions.…”