Randomized trial of preinduction cervical ripening: misoprostol vs oxytocin

Maternal and Neonatal Outcomes in Nulliparous Participants Undergoing Labor Induction by Cervical Ripening Method

OBJECTIVE

 This study aimed to evaluate maternal and neonatal outcomes by method of cervical ripening for labor induction among low-risk nulliparous individuals.

STUDY DESIGN

 This is a secondary analysis of a multicenter randomized trial of labor induction at 39 weeks versus expectant management in low-risk nulliparous participants. Participants undergoing cervical ripening for labor induction in either group were included. Participants were excluded for preripening membrane rupture, abruption, chorioamnionitis, fetal demise, or cervical dilation ≥3.5 cm. Cervical ripening was defined by the initial method used: prostaglandin only (PGE; referent), Foley with concurrent prostaglandin (Foley-PGE), Foley only (Foley), and Foley with concurrent oxytocin (Foley-oxytocin). Coprimary outcomes were adverse maternal and neonatal composites. Secondary outcomes included cesarean delivery and length of labor and delivery (L&D) stay. Multivariable analysis was used to adjust for patient characteristics.

RESULTS

 Of 6,106 participants included in the trial, 2,376 (38.9%) met criteria for this analysis. Of these, 1,247 (52.4%) had cervical ripening with PGE, 290 (12.2%) had Foley-PGE, 385 (16.2%) had Foley, and 454 (19.1%) had Foley-oxytocin. The maternal composite outcome was similar among participants who received Foley-PGE (24.1%, adjusted relative risk [aRR] = 1.21, 95% confidence interval [CI]: 0.96-1.52), Foley (21.3%, aRR = 1.16, 95% CI: 0.92-1.45), or Foley-oxytocin (19.4%, aRR = 1.04, 95% CI: 0.83-1.29), compared with PGE (19.7%). The neonatal composite outcome was less frequent in participants who received the Foley-PGE (2.4%, aRR = 0.35, 95% CI: 0.16-0.75) or Foley (3.6%, aRR = 0.51, 95% CI: 0.29-0.89) but did not reach statistical significance for participants who received Foley-oxytocin (4.6%, aRR = 0.63, 95% CI: 0.40-1.01) compared with PGE only (6.8%). Participants who received Foley-PGE or Foley-oxytocin had a shorter L&D stay (adjusted mean difference = -1.97 hours, 95% CI: -3.45 to -0.49 and -5.92 hours, 95% CI: -7.07 to -4.77, respectively), compared with PGE.

CONCLUSION

 In term low-risk nulliparous participants, Foley alone or concurrent with PGE is associated with a lower risk of adverse neonatal outcomes than with PGE alone. Length of L&D stay was the shortest with concurrent Foley-oxytocin.

KEY POINTS

· Adverse maternal outcomes are similar among different methods of cervical ripening in low-risk women.. · Adverse neonatal outcomes are less frequent with use of Foley alone or in combination with PGE.. · The use of Foley alone, or in combination with other agents, appears to be beneficial..

Prediction Model for Vaginal Birth After Induction of Labor in Women With Hypertensive Disorders of Pregnancy

OBJECTIVE

To identify characteristics associated with vaginal delivery compared with cesarean delivery after labor induction among women with hypertensive disorders of pregnancy and to develop and validate a prediction model to assist in clinical care.

METHODS

We studied a retrospective cohort of women with singleton pregnancies who had hypertensive disorders of pregnancy and who underwent induction of labor at 34 weeks of gestation or more from January 1, 2002, to March 31, 2013. Exclusion criteria included spontaneous labor, prelabor cesarean delivery, and known fetal anomalies. The study cohort was randomly divided into two groups; 70% of pregnancies were used to identify characteristics associated with vaginal delivery and develop a prediction model, and 30% were used to internally validate the model. Candidate predictors were limited to those associated with cesarean delivery and were available to a practitioner at time of induction. Stepwise backward logistic regression was used to build the most parsimonious model predicting cesarean delivery. Hosmer-Lemeshow test was used to assess goodness-of-fit. Model discrimination was evaluated using the concordance index and displayed through the area under the receiver operating characteristic curve (AUC).

RESULTS

Of the 1,357 women meeting study criteria, 974 (71.8%) had a vaginal delivery. The final model consisted of eight variables: maternal age, body mass index, gestational age, intrapartum magnesium sulfate for seizure prophylaxis, need for cervical ripening, prior cesarean delivery and cervical dilation, and effacement. Model calibration and discrimination were satisfactory with Hosmer-Lemeshow test P=.35 and with a 95% CI, an AUC of 0.76 (0.73-0.79). Among those with predicted probability of cesarean delivery of 20% or less, 89.5% had a vaginal delivery. Internal validation demonstrated similar discriminatory ability.

CONCLUSION

Using information available before labor induction, and contingent on future external validation, our model can help women better understand their likelihood of vaginal delivery success when undergoing induction of labor for hypertensive disorders of pregnancy.

Challenges and Limitations of Clinical Trials on Labor Induction: A Review of the Literature

Induction of labor is a common obstetric procedure performed in nearly a quarter of all deliveries in the United States. Pharmacological (prostaglandins, oxytocin) and/or mechanical methods (balloon catheters) are commonly used for labor induction; however, there is ongoing debate as to which method is the safest and most effective. This narrative review discusses key limitations of published trials on labor induction, including the lack of well-designed randomized controlled trials directly comparing specific methods of induction, heterogeneous trial populations, and wide variation in the protocols used and outcomes reported. Furthermore, the majority of published trials were underpowered to detect significant differences in the most clinically relevant efficacy and safety outcomes (e.g., cesarean delivery, neonatal mortality). By identifying the limitations of labor induction trials, we hope to highlight the importance of quality published data to better inform guidelines and drive evidence-based treatment decisions.

Which method is best for the induction of labour? A systematic review, network meta-analysis and cost-effectiveness analysis

BACKGROUND

More than 150,000 pregnant women in England and Wales have their labour induced each year. Multiple pharmacological, mechanical and complementary methods are available to induce labour.

OBJECTIVE

To assess the relative effectiveness, safety and cost-effectiveness of labour induction methods and, data permitting, effects in different clinical subgroups.

METHODS

We carried out a systematic review using Cochrane methods. The Cochrane Pregnancy and Childbirth Group's Trials Register was searched (March 2014). This contains over 22,000 reports of controlled trials (published from 1923 onwards) retrieved from weekly searches of OVID MEDLINE (1966 to current); Cochrane Central Register of Controlled Trials (The Cochrane Library); EMBASE (1982 to current); Cumulative Index to Nursing and Allied Health Literature (1984 to current); ClinicalTrials.gov; the World Health Organization International Clinical Trials Registry Portal; and hand-searching of relevant conference proceedings and journals. We included randomised controlled trials examining interventions to induce labour compared with placebo, no treatment or other interventions in women eligible for third-trimester induction. We included outcomes relating to efficacy, safety and acceptability to women. In addition, for the economic analysis we searched the Database of Abstracts of Reviews of Effects, and Economic Evaluations Databases, NHS Economic Evaluation Database and the Health Technology Assessment database. We carried out a network meta-analysis (NMA) using all of the available evidence, both direct and indirect, to produce estimates of the relative effects of each treatment compared with others in a network. We developed a de novo decision tree model to estimate the cost-effectiveness of various methods. The costs included were the intervention and other hospital costs incurred (price year 2012-13). We reviewed the literature to identify preference-based utilities for the health-related outcomes in the model. We calculated incremental cost-effectiveness ratios, expected costs, utilities and net benefit. We represent uncertainty in the optimal intervention using cost-effectiveness acceptability curves.

RESULTS

We identified 1190 studies; 611 were eligible for inclusion. The interventions most likely to achieve vaginal delivery (VD) within 24 hours were intravenous oxytocin with amniotomy [posterior rank 2; 95% credible intervals (CrIs) 1 to 9] and higher-dose (≥ 50 µg) vaginal misoprostol (rank 3; 95% CrI 1 to 6). Compared with placebo, several treatments reduced the odds of caesarean section, but we observed considerable uncertainty in treatment rankings. For uterine hyperstimulation, double-balloon catheter had the highest probability of being among the best three treatments, whereas vaginal misoprostol (≥ 50 µg) was most likely to increase the odds of excessive uterine activity. For other safety outcomes there were insufficient data or there was too much uncertainty to identify which treatments performed 'best'. Few studies collected information on women's views. Owing to incomplete reporting of the VD within 24 hours outcome, the cost-effectiveness analysis could compare only 20 interventions. The analysis suggested that most interventions have similar utility and differ mainly in cost. With a caveat of considerable uncertainty, titrated (low-dose) misoprostol solution and buccal/sublingual misoprostol had the highest likelihood of being cost-effective.

LIMITATIONS

There was considerable uncertainty in findings and there were insufficient data for some planned subgroup analyses.

CONCLUSIONS

Overall, misoprostol and oxytocin with amniotomy (for women with favourable cervix) is more successful than other agents in achieving VD within 24 hours. The ranking according to safety of different methods was less clear. The cost-effectiveness analysis suggested that titrated (low-dose) oral misoprostol solution resulted in the highest utility, whereas buccal/sublingual misoprostol had the lowest cost. There was a high degree of uncertainty as to the most cost-effective intervention.

FUTURE WORK

Future trials should be powered to detect a method that is more cost-effective than misoprostol solution and report outcomes included in this NMA.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005116.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Comparison of induction of labor methods for unfavorable cervices in trial of labor after cesarean delivery

OBJECTIVE

To compare induction of labor methods in patients attempting a trial of labor after cesarean (TOLAC) with an unfavorable cervix.

METHODS

This is a retrospective cohort study from patients attempting TOLAC from 2009 to 2013. Patients with a simplified Bishop score of three or less where labor was initiated with either a Cook balloon or oxytocin were included. Our primary outcome was mode of delivery. Our secondary outcomes included duration of labor and multiple maternal and neonatal morbidities.

RESULTS

Two-hundred and fourteen women met inclusion criteria: 150 received oxytocin and 64 had the Cook balloon placed. The vaginal birth after cesarean delivery rate was significantly higher in the oxytocin group at 70.7% versus 50.0% in the Cook balloon group (p = 0.004). In the multivariable analysis, odds for cesarean delivery were two times higher with the Cook balloon than with oxytocin (Adjusted OR = 2.09, 95% CI = 1.05-4.18, p = 0.036). The duration of labor was longer with the Cook balloon versus oxytocin (21.9 versus 16.3 hours, p = 0.0002). There were no significant differences in maternal and neonatal health outcomes.

CONCLUSION

Oxytocin induction of labor was associated with a higher rate of vaginal delivery and a shorter duration of labor compared to the Cook balloon in women undergoing TOLAC with an unfavorable cervix.

In vitro myometrial contractility profiles of different pharmacological agents used for induction of labor

OBJECTIVE

To investigate the effects of different pharmacological induction agents on myometrial contractility.

STUDY DESIGN

Myometrial biopsies were obtained from 13 term nonlaboring women undergoing scheduled cesarean delivery. Tissue strips were suspended in organ chambers for isometric tension recording. The effects of cumulative doses (10-10 mol/L to 10-5 mol/L) of prostaglandin E1 (PGE1), E2 (PGE2), and oxytocin on spontaneous uterine contractility were determined. Areas under the contraction curve were compared using one-way analysis of variance on ranks with Dunn post hoc test.

RESULTS

Oxytocin-induced myometrial contractility was superior to PGE1, PGE2, and time controls (CTR) at all the concentrations tested. When only prostaglandins were compared with CTR, PGE1 10-5 mol/L increased myometrial contractility, and PGE2 had no effects.

CONCLUSION

Oxytocin and prostaglandins have different effects on myometrial contractility accounting for different mechanisms of action and side effects. The increased uterine contractility observed with PGE1 as compared with PGE2 can contribute to explain the higher success of vaginal delivery.

[Adding parity to the Bishop score for term labor induction: a retrospective study]

OBJECTIVE

To evaluate the interest to add parity to the Bishop score before induction of labor by intravenous oxytocin.

PATIENTS AND METHODS

This retrospective cohort study compared cesarean section rate for induction failure by intravenous oxytocin in nulliparous and multiparous with modified Bishop score from 7 to 9. The modified Bishop score is calculated by adding 2 points to the Bishop score if the patient had a previous vaginal delivery and 0 point in nulliparous.

RESULTS

Over 2 years, 468 patients were included (201 nulliparous and 267 multiparous). Cesarean section rate for induction failure was higher for nulliparous with a modified Bishop score equal to 7 or varying between 7 and 9. These results confirm that parity is an important predicting factor of successful labor induction. In multiparous, cesarean section rates for induction failure were not significantly different with Bishop score or modified Bishop score equal to 7.

CONCLUSION

Adding 2 points for multiparity at the Bishop score did not increase cesarean for failure of labor induction with intravenous oxytocin with a modified Bishop score from 7 to 9.

Effect of a comprehensive obstetric patient safety program on compensation payments and sentinel events

Our objective was to describe a comprehensive obstetric patient safety program and its effect on reducing compensation payments and sentinel adverse events. From 2003 to 2009, we implemented a comprehensive obstetric patient safety program at our institution with multiple integrated components. To evaluate its effect on compensation payments and sentinel events, we gathered data on compensation payments and sentinel events retrospectively from 2003, when the program was initiated, through 2009. Average yearly compensation payments decreased from $27,591,610 between 2003-2006 to $2,550,136 between 2007-2009, sentinel events decreased from 5 in 2000 to none in 2008 and 2009. Instituting a comprehensive obstetric patient safety program decreased compensation payments and sentinel events resulting in immediate and significant savings.

Vaginal misoprostol for cervical ripening and induction of labour

BACKGROUND

Misoprostol (Cytotec, Searle) is a prostaglandin E1 analogue widely used for off-label indications such as induction of abortion and of labour. This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology.

OBJECTIVES

To determine the effects of vaginal misoprostol for third trimester cervical ripening or induction of labour.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group's Trials Register (November 2008) and bibliographies of relevant papers. We updated this search on 30 April 2010 and added the results to the awaiting classification section.

SELECTION CRITERIA

Clinical trials comparing vaginal misoprostol used for third trimester cervical ripening or labour induction with placebo/no treatment or other methods listed above it on a predefined list of labour induction methods.

DATA COLLECTION AND ANALYSIS

We developed a strategy to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction.We used fixed-effect Mantel-Haenszel meta-analysis for combining dichotomous data.If we identified substantial heterogeneity (I² greater than 50%), we used a random-effects method.

MAIN RESULTS

We included 121 trials. The risk of bias must be kept in mind as only 13 trials were double blind.Compared to placebo, misoprostol was associated with reduced failure to achieve vaginal delivery within 24 hours (average relative risk (RR) 0.51, 95% confidence interval (CI) 0.37 to 0.71). Uterine hyperstimulation, without fetal heart rate (FHR) changes, was increased (RR 3.52 95% CI 1.78 to 6.99).Compared with vaginal prostaglandin E2, intracervical prostaglandin E2 and oxytocin, vaginal misoprostol was associated with less epidural analgesia use, fewer failures to achieve vaginal delivery within 24 hours and more uterine hyperstimulation. Compared with vaginal or intracervical prostaglandin E2, oxytocin augmentation was less common with misoprostol and meconium-stained liquor more common.Lower doses of misoprostol compared to higher doses were associated with more need for oxytocin augmentation and less uterine hyperstimulation, with and without FHR changes.We found no information on women's views.

AUTHORS' CONCLUSIONS

Vaginal misoprostol in doses above 25 mcg four-hourly was more effective than conventional methods of labour induction, but with more uterine hyperstimulation. Lower doses were similar to conventional methods in effectiveness and risks. The authors request information on cases of uterine rupture known to readers. The vaginal route should not be researched further as another Cochrane review has shown that the oral route of administration is preferable to the vaginal route. Professional and governmental bodies should agree guidelines for the use of misoprostol, based on the best available evidence and local circumstances.

Induction of labor with vaginal misoprostol plus oxytocin versus oxytocin alone

OBJECTIVE

To compare the effect of an oxytocin infusion alone or preceded by an intravaginal application of misoprostol for labor induction in women with term pregnancies and a low Bishop score.

METHODS

This study randomized 100 multiparous women with singleton pregnancies over 38 weeks and a Bishop score less than 6 to receive either a single 50-microg dose of misoprostol intravaginally 3 hours before initiation of the oxytocin infusion or only an oxytocin infusion. The time from induction to delivery, the route of delivery, and maternal and fetal outcomes were analyzed.

RESULTS

The mean time from induction to delivery was 9.36+/-1.97 hours in the misoprostol plus oxytocin group and 11.08+/-3.23 in the oxytocin alone group (P=0.002). The rates of vaginal delivery, 1- and 5-minute Agpar scores, placental abruption, and postpartum hemorrhage were similar between the 2 groups, as were the rates of admission to the neonatal intensive care unit. There were no cases of perinatal asphyxia.

CONCLUSION

A 50-microg intravaginal application of misoprostol before starting the oxytocin infusion is a more effective method of labor induction than an oxytocin infusion alone for our study population.