Oral versus vaginal misoprostol for induction of labor: a double-blind randomized controlled trial

Vaginal Compared With Oral Misoprostol Induction at Term: A Cluster Randomized Controlled Trial

OBJECTIVE

To evaluate efficacy in achieving vaginal delivery with a standardized vaginal compared with oral misoprostol regimen for labor induction at term.

METHODS

In this single-center, cluster randomized trial, we randomized induction method by week among individuals with gestational age of 37 weeks or more, cervical dilation of 2 cm or less, intact membranes, and indication for delivery to either oral (100 micrograms every 4 hours for up to two doses), or vaginal (25 micrograms every 3 hours for up to five doses) misoprostol regimens, followed by a standardized oxytocin protocol. Individuals with an antepartum stillbirth, major fetal anomalies, malpresentation, ruptured membranes, nonreassuring fetal status, or contraindication to prostaglandin were excluded. The primary outcome was vaginal delivery at first induction attempt. Secondary outcomes included time to delivery, need for oxytocin, chorioamnionitis, and adverse maternal and neonatal outcomes. Outcomes were recorded at the individual level and adjusted for clustering, with analysis by intention to treat.

RESULTS

Between May 24, 2021, to September 19, 2022, 1,322 women were randomized to vaginal misoprostol in 33 clusters and 1,224 to oral misoprostol in 37 clusters. Demographic characteristics or initial cervical dilation did not differ between groups. The primary outcome did not differ between induction regimens and occurred in 1,032 (78.1%) of the vaginal misoprostol arm and 945 (77.2%) of the oral misoprostol arm (adjusted relative risk [RR] 1.01, 95% CI, 0.97-1.05). Tachysystole with fetal heart rate changes occurred less frequently with vaginal compared with oral misoprostol (3.5% vs 5.9%, adjusted RR 0.59, 95% CI, 0.40-0.87). Time to delivery did not differ between groups. Oxytocin was less frequently required before delivery in the vaginal misoprostol group (68.8% vs 78.4%, adjusted RR 0.88, 95% CI, 0.84-0.92).

CONCLUSION

Induction of labor with vaginal compared with oral misoprostol protocols did not increase the frequency of vaginal delivery at term but did reduce the need for oxytocin use before delivery.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT04755218.

Efficacy and safety of oral and sublingual versus vaginal misoprostol for induction of labour: a systematic review and meta-analysis

Objective

Misoprostol is a synthetic PGE1 analogue that is used for induction of labour. Current guidelines support the use of doses that do not exceed 25 mcg in order to limit maternal and neonatal adverse outcomes. The present meta-analysis investigates the efficacy and safety of oral compared to vaginally inserted misoprostol in terms of induction of labor and adverse peripartum outcomes.

Methods

We searched Medline, Scopus, the Cochrane Central Register of Controlled Trials CENTRAL, Google Scholar, and Clinicaltrials.gov databases from inception till April 2022. Randomized controlled trials that assessed the efficacy of oral misoprostol (per os or sublingual) compared to vaginally inserted misoprostol. Effect sizes were calculated in R. Sensitivity analysis was performed to evaluate the possibility of small study effects, p-hacking. Meta-regression and subgroup analysis according to the dose of misoprostol was also investigated. The methodological quality of the included studies was assessed by two independent reviewers using the risk of bias 2 tool. Quality of evidence for primary outcomes was evaluated under the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework, ranging from very low to high.

Results

Overall, 57 studies were included that involved 10,975 parturient. Their risk of bias ranged between low-moderate. There were no differences among the routes of intake in terms of successful vaginal delivery within 24 h (RR 0.90, 95% CI 0.80) and cesarean section rates (RR 0.92, 95% CI 0.82, 1.04). Sublingual misoprostol was superior compared to vaginal misoprostol in reducing the interval from induction to delivery (MD – 1.11 h, 95% CI – 2.06, – 0.17). On the other hand, per os misoprostol was inferior compared to vaginal misoprostol in terms of this outcome (MD 3.45 h, 95% CI 1.85, 5.06). Maternal and neonatal morbidity was not affected by the route or dose of misoprostol.

Conclusion

The findings of our study suggest that oral misoprostol intake is equally safe to vaginal misoprostol in terms of inducing labor at term. Sublingual intake seems to outperform the per os and vaginal routes without increasing the accompanying morbidity. Increasing the dose of misoprostol does not seem to increase its efficacy.

Clinical trial registration

Open Science Framework (https://doi.org/10.17605/OSF.IO/V9JHF).

Safety and efficacy of double-balloon catheter for cervical ripening: a Bayesian network meta-analysis of randomized controlled trials

BACKGROUND

Various methods are used for cervical ripening during the induction of labor. Mechanical and pharmacological methods are commonly used for cervical ripening. A double-balloon catheter was specifically developed to ripen the cervix and induce labor; however, the efficacy of the double-balloon catheter in cervical ripening compared to other methods is unknown.

METHODS

We searched five databases and performed a Bayesian network meta-analysis. Six interventions (double-balloon catheter, Foley catheter, oral misoprostol, vaginal misoprostol, dinoprostone, and double-balloon catheter combined with oral misoprostol) were included in the search. The primary outcomes were cesarean delivery rate and time from intervention-to-birth. The secondary outcomes were as follows: Bishop score increment; achieving a vaginal delivery within 24 h; uterine hyperstimulation with fetal heart rate changes; need for oxytocin augmentation; instrumental delivery; meconium staining; chorioamnionitis; postpartum hemorrhage; low Apgar score; neonatal intensive care unit admission; and arterial pH.

RESULTS

Forty-eight randomized controlled trials involving 11,482 pregnant women were identified. The cesarean delivery rates of the cervical ripening with a double-balloon catheter and oral misoprostol, oral misoprostol, and vaginal misoprostol were significantly lower than cervical ripening with a Foley catheter (OR = 0.48, 95% CI: 0.23-0.96; OR = 0.74, 95% CI: 0.58-0.93; and OR = 0.79, 95% CI: 0.64-0.97, respectively; all P < 0.05). The time from intervention-to-birth of vaginal misoprostol was significantly shorter than the other five cervical ripening methods. Vaginal misoprostol and oral misoprostol increased the risk of uterine hyperstimulation with fetal heart rate changes compared to a Foley catheter. A double-balloon catheter with or without oral misoprostol had similar outcomes, including uterine hyperstimulation with fetal heart rate changes compared to a Foley catheter.

CONCLUSION

Double-balloon catheter did not show superiority when compared with other single method in primary and secondary outcomes of labor induction. The combination of double-balloon catheter with oral misoprostol was significantly reduced the rate of cesarean section compared to Foley catheter without increased risk of uterine hyperstimulation with fetal heart rate changes, which was shown in oral or vaginal misoprostol.

Low-dose oral misoprostol for induction of labour

BACKGROUND

Misoprostol given orally is a commonly used labour induction method. Our Cochrane Review is restricted to studies with low-dose misoprostol (initially ≤ 50 µg), as higher doses pose unacceptably high risks of uterine hyperstimulation.

OBJECTIVES

To assess the efficacy and safety of low-dose oral misoprostol for labour induction in women with a viable fetus in the third trimester of pregnancy.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov,  the WHO International Clinical Trials Registry Platform (14 February 2021) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised trials comparing low-dose oral misoprostol (initial dose ≤ 50 µg) versus placebo, vaginal dinoprostone, vaginal misoprostol, oxytocin, or mechanical methods; or comparing oral misoprostol protocols (one- to two-hourly versus four- to six-hourly; 20 µg to 25 µg versus 50 µg; or 20 µg hourly titrated versus 25 µg two-hourly static).

DATA COLLECTION AND ANALYSIS

Using Covidence, two review authors independently screened reports, extracted trial data, and performed quality assessments. Our primary outcomes were vaginal birth within 24 hours, caesarean section, and hyperstimulation with foetal heart changes.

MAIN RESULTS

We included 61 trials involving 20,026 women. GRADE assessments ranged from moderate- to very low-certainty evidence, with downgrading decisions based on imprecision, inconsistency, and study limitations. Oral misoprostol versus placebo/no treatment (four trials; 594 women) Oral misoprostol may make little to no difference in the rate of caesarean section (risk ratio (RR) 0.81, 95% confidence interval (CI) 0.59 to 1.11; 4 trials; 594 women; moderate-certainty evidence), while its effect on uterine hyperstimulation with foetal heart rate changes is uncertain (RR 5.15, 95% CI 0.25 to 105.31; 3 trials; 495 women; very low-certainty evidence). Vaginal births within 24 hours was not reported. In all trials, oxytocin could be commenced after 12 to 24 hours and all women had pre-labour ruptured membranes. Oral misoprostol versus vaginal dinoprostone (13 trials; 9676 women) Oral misoprostol probably results in fewer caesarean sections (RR 0.84, 95% CI 0.78 to 0.90; 13 trials, 9676 women; moderate-certainty evidence). Subgroup analysis indicated that 10 µg to 25 µg (RR 0.80, 95% CI 0.74 to 0.87; 9 trials; 8652 women) may differ from 50 µg (RR 1.10, 95% CI 0.91 to 1.34; 4 trials; 1024 women) for caesarean section. Oral misoprostol may decrease vaginal births within 24 hours (RR 0.93, 95% CI 0.87 to 1.00; 10 trials; 8983 women; low-certainty evidence) and hyperstimulation with foetal heart rate changes (RR 0.49, 95% CI 0.40 to 0.59; 11 trials; 9084 women; low-certainty evidence). Oral misoprostol versus vaginal misoprostol (33 trials; 6110 women) Oral use may result in fewer vaginal births within 24 hours (average RR 0.81, 95% CI 0.68 to 0.95; 16 trials, 3451 women; low-certainty evidence), and less hyperstimulation with foetal heart rate changes (RR 0.69, 95% CI 0.53 to 0.92, 25 trials, 4857 women, low-certainty evidence), with subgroup analysis suggesting that 10 µg to 25 µg orally (RR 0.28, 95% CI 0.14 to 0.57; 6 trials, 957 women) may be superior to 50 µg orally (RR 0.82, 95% CI 0.61 to 1.11; 19 trials; 3900 women). Oral misoprostol probably does not increase caesarean sections overall (average RR 1.00, 95% CI 0.86 to 1.16; 32 trials; 5914 women; low-certainty evidence) but likely results in fewer caesareans for foetal distress (RR 0.74, 95% CI 0.55 to 0.99; 24 trials, 4775 women). Oral misoprostol versus intravenous oxytocin (6 trials; 737 women, 200 with ruptured membranes) Misoprostol may make little or no difference to vaginal births within 24 hours (RR 1.12, 95% CI 0.95 to 1.33; 3 trials; 466 women; low-certainty evidence), but probably results in fewer caesarean sections (RR 0.67, 95% CI 0.50 to 0.90; 6 trials; 737 women; moderate-certainty evidence). The effect on hyperstimulation with foetal heart rate changes is uncertain (RR 0.66, 95% CI 0.19 to 2.26; 3 trials, 331 women; very low-certainty evidence). Oral misoprostol versus mechanical methods (6 trials; 2993 women) Six trials compared oral misoprostol to transcervical Foley catheter. Misoprostol may increase vaginal birth within 24 hours (RR 1.32, 95% CI 0.98 to 1.79; 4 trials; 1044 women; low-certainty evidence), and probably reduces the risk of caesarean section (RR 0.84, 95% CI 0.75 to 0.95; 6 trials; 2993 women; moderate-certainty evidence). There may be little or no difference in hyperstimulation with foetal heart rate changes (RR 1.31, 95% CI 0.78 to 2.21; 4 trials; 2828 women; low-certainty evidence). Oral misoprostol one- to two-hourly versus four- to six-hourly (1 trial; 64 women) The evidence on hourly titration was very uncertain due to the low numbers reported. Oral misoprostol 20 µg hourly titrated versus 25 µg two-hourly static (2 trials; 296 women) The difference in regimen may have little or no effect on the rate of vaginal births in 24 hours (RR 0.97, 95% CI 0.80 to 1.16; low-certainty evidence). The evidence is of very low certainty for all other reported outcomes.

AUTHORS' CONCLUSIONS

Low-dose oral misoprostol is probably associated with fewer caesarean sections (and therefore more vaginal births) than vaginal dinoprostone, and lower rates of hyperstimulation with foetal heart rate changes. However, time to birth may be increased, as seen by a reduced number of vaginal births within 24 hours. Compared to transcervical Foley catheter, low-dose oral misoprostol is associated with fewer caesarean sections, but equivalent rates of hyperstimulation. Low-dose misoprostol given orally rather than vaginally is probably associated with similar rates of vaginal birth, although rates may be lower within the first 24 hours. However, there is likely less hyperstimulation with foetal heart changes, and fewer caesarean sections performed due to foetal distress. The best available evidence suggests that low-dose oral misoprostol probably has many benefits over other methods for labour induction. This review supports the use of low-dose oral misoprostol for induction of labour, and demonstrates the lower risks of hyperstimulation than when misoprostol is given vaginally. More trials are needed to establish the optimum oral misoprostol regimen, but these findings suggest that a starting dose of 25 µg may offer a good balance of efficacy and safety.

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.

A randomised double-blind placebo-controlled trial comparing stepwise oral misoprostol with vaginal misoprostol for induction of labour

A comparison of induction of labour (IOL) using three doses of 25 µg vaginal misoprostol inserted at intervals of 4 h or more with a stepwise oral regime starting with 50 µg followed by two doses of 100 µg was studied in a double-blind placebo-controlled trial in a tertiary centre in South India. Primary outcome was vaginal delivery in 24 h. Significantly more women in the first group required oxytocin augmentation and a third dose of the drug than women in the second group. Uterine tachysystole and other maternal and neonatal complications were similar. Thus it is concluded that women induced with oral, as compared to vaginal misoprostol are more likely to labour without oxytocin.

Oral versus vaginal misoprostol for induction of labor in Enugu, Nigeria: a randomized controlled trial

OBJECTIVE

The study aimed at comparing the effectiveness and maternal satisfaction of oral misoprostol with vaginal misoprostol for induction of labor at term.

MATERIALS AND METHODS

A randomized controlled trial of 140 term pregnant women at the University of Nigeria Teaching Hospital Enugu, Nigeria, was conducted from April 2011 to May 2012. The women were equally randomized into two groups (A and B) to receive oral and vaginal misoprostol, respectively.

RESULTS

The vaginal route reduced the mean induction-vaginal delivery interval by four-and-half hours (20.7 ± 12.1 vs. 16.2 ± 10.4; mean difference: 4.50, 95% CI 0.63-0.82; p = 0.02). Furthermore, the mean dose of misoprostol required to achieve induction of labor and the mean duration of oxytocin augmentation when indicated were significantly less in the vaginal group than in the oral group (2.5 ± 1.3 vs. 2.0 ± 1.1; mean difference: 0.50, 95% CI 0.10-0.90; p = 0.02 and 4.6 ± 3.2 vs. 3.4 ± 3.1; mean difference: 1.20, 95% CI 0.15-0.23; p = 0.03 respectively). However, neonatal complications and maternal satisfaction were similar between the two groups.

CONCLUSION

Both routes of administration are effective in the induction of labor at term and have comparable maternal satisfaction. However, the vaginal route has the added advantage of shorter induction-delivery interval among others, and thus should be highly considered when induction of labor is indicated at term.

Oral misoprostol for induction of labour

BACKGROUND

Misoprostol is an orally active prostaglandin. In most countries misoprostol is not licensed for labour induction, but its use is common because it is cheap and heat stable.

OBJECTIVES

To assess the use of oral misoprostol for labour induction in women with a viable fetus.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (17 January 2014).

SELECTION CRITERIA

Randomised trials comparing oral misoprostol versus placebo or other methods, given to women with a viable fetus for labour induction.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial data, using centrally-designed data sheets.

MAIN RESULTS

Overall there were 76 trials (14,412) women) which were of mixed quality.In nine trials comparing oral misoprostol with placebo (1109 women), women using oral misoprostol were more likely to give birth vaginally within 24 hours (risk ratio (RR) 0.16, 95% confidence interval (CI) 0.05 to 0.49; one trial; 96 women), need less oxytocin (RR 0.42, 95% CI 0.37 to 0.49; seven trials; 933 women) and have a lower caesarean section rate (RR 0.72, 95% CI 0.54 to 0.95; eight trials; 1029 women).In 12 trials comparing oral misoprostol with vaginal dinoprostone (3859 women), women given oral misoprostol were less likely to need a caesarean section (RR 0.88, 95% CI 0.78 to 0.99; 11 trials; 3592 women). There was some evidence that they had slower inductions, but there were no other statistically significant differences.Nine trials (1282 women) compared oral misoprostol with intravenous oxytocin. The caesarean section rate was significantly lower in women who received oral misoprostol (RR 0.77, 95% CI 0.60 to 0.98; nine trials; 1282 women), but they had increased rates of meconium-stained liquor (RR 1.65, 95% CI 1.04 to 2.60; seven trials; 1172 women).Thirty-seven trials (6417 women) compared oral and vaginal misoprostol and found no statistically significant difference in the primary outcomes of serious neonatal morbidity/death or serious maternal morbidity or death. The results for vaginal birth not achieved in 24 hours, uterine hyperstimulation with fetal heart rate (FHR) changes, and caesarean section were highly heterogenous - for uterine hyperstimulation with FHR changes this was related to dosage with lower rates in those with lower doses of oral misoprostol. However, there were fewer babies born with a low Apgar score in the oral group (RR 0.60, 95% CI 0.44 to 0.82; 19 trials; 4009 babies) and a decrease in postpartum haemorrhage (RR 0.57, 95% CI 0.34 to 0.95; 10 trials; 1478 women). However, the oral misoprostol group had an increase in meconium-stained liquor (RR 1.22, 95% CI 1.03 to 1.44; 24 trials; 3634 women).

AUTHORS' CONCLUSIONS

Oral misoprostol as an induction agent is effective at achieving vaginal birth. It is more effective than placebo, as effective as vaginal misoprostol and results in fewer caesarean sections than vaginal dinoprostone or oxytocin.Where misoprostol remains unlicensed for the induction of labour, many practitioners will prefer to use a licensed product like dinoprostone. If using oral misoprostol, the evidence suggests that the dose should be 20 to 25 mcg in solution. Given that safety is the primary concern, the evidence supports the use of oral regimens over vaginal regimens. This is especially important in situations where the risk of ascending infection is high and the lack of staff means that women cannot be intensely monitored.

A prospective double blind study using oral versus vaginal misoprostol for labour induction

This prospective double blind study was undertaken to compare the safety and efficacy of oral vs vaginal misoprostol in equivalent doses (50 microg) for induction of labour. A total of 128 term pregnancies with indication for induction of labour were allocated to two groups to receive 50 microg misoprostol orally or vaginally, every 4 h until adequate contractions were achieved or a maximum of 200 microg dose. Induction to delivery interval was significantly shorter in the vaginal group compared with the oral group (14.6 h vs 22.5 h; p < 0.001). There was no significant difference between the groups with respect to mode of delivery, neonatal outcome and maternal side-effects. However, the incidence of abnormal contractility pattern was more common in the vaginal group (10/68, 14.6%) as compared with the oral group (4/60, 6.6%) (p = 0.146).

Randomized trial of buccal versus vaginal misoprostol for induction of second trimester abortion

BACKGROUND

We evaluated the efficacy and acceptability of repeat doses of buccal misoprostol compared to vaginal misoprostol for second trimester pregnancy termination by induction.

STUDY DESIGN

Women requesting termination of a pregnancy between 18 and 22 weeks gestation were approached for participation. All women received 400 mcg misoprostol vaginally on admission. Participants were randomized to receive subsequent doses of 200 mcg misoprostol every 6 h either buccally or vaginally. All participants completed an acceptability survey.

RESULTS

Sixty-four women participated. The mean gestational age was 19.7 weeks. The median time to abortion in the buccal group was 15 h, which was not significantly different (p=0.44) from the vaginal-only group of 12 h. Most women in both groups preferred their allocated administrative route.

CONCLUSION

Repeat doses of buccal misoprostol are as effective as vaginal misoprostol in inducing abortions in the midtrimester and are highly acceptable to most women. It is reasonable to offer both options to women.

Oral Misoprostol Administration for Labor Induction

Using oral agents for induction of labor would reduce the need for repeated vaginal examinations; this is more acceptable to women and could reduce infection rates. A systematic review was conducted of 41 randomized trials comparing oral misoprostol to other induction agents. Oral misoprostol is effective at achieving vaginal delivery, and may have benefits over both vaginal and intracervical dinoprostone. Although it does not achieve vaginal delivery as quickly as vaginal misoprostol, the rates of hyperstimulation are lower when using comparable doses. As the primary consideration should be safety rather than speed, an oral regimen using a maximum of 50 mcg 4 hourly is recommended.

What Is A Failed Labor Induction?

Criteria for failed labor induction have not been standardized. The increasing prevalence of labor induction and the lack of a definition for failed induction contribute to unnecessary abdominal deliveries. Labor duration, cervical dilation, and uterine activity necessary to attain the active phase are reviewed. A practical definition of failed induction of labor is suggested.

The routine use of oxytocin after oral misoprostol for labour induction in women with an unfavourable cervix is not of benefit

BACKGROUND

Induction of labour with misoprostol is often augmented with oxytocin with the possible consequence of uterine hypercontractility. It is important to determine whether the use of oxytocin in this circumstance has benefit as well as risk.

AIM

To compare two regimens for labour induction in women with an unfavourable cervix: oral misoprostol vs. oral misoprostol routinely followed by oxytocin.

METHODS

A prospective randomised trial in which 200 women with an unfavourable cervix received either oral misoprostol 25 microg every 3 h (group 1, n = 100) or two such doses routinely followed by oxytocin (group 2, n = 100). Outcomes included change in Bishop score, induction delivery interval, oxytocin requirement, contraction abnormalities, mode of delivery and neonatal outcome.

RESULT

The improvement in Bishop score with two misoprostol doses in all 200 women was highly significant (2.9 +/- 1.5 to 6.6 +/- 1.9, P < 0.0001). The induction delivery interval, Caesarean delivery rate, vaginal delivery rate within 24 h, contraction abnormalities and neonatal outcome were similar in both groups. Contraction abnormalities were remarkably low with either regimen (1%). Routine addition of oxytocin 3 h after the second misoprostol dose (group 2) resulted in the maximum oxytocin dose (64 mU/min) being given to more women (66% in group 2; 36% in group 1).

CONCLUSION

There was no benefit of routine addition of oxytocin after two doses of misoprostol. Reduced oxytocin requirement was observed when it was added only if needed. Both regimens achieved 85-87% vaginal deliveries with low incidence of hypercontractility.

Oral misoprostol for induction of labour

BACKGROUND

Misoprostol is a synthetic prostaglandin that can be given orally or vaginally. In most countries misoprostol has not been licensed for use in pregnancy, but its unlicensed use is common because misoprostol is cheap, stable at room temperature and effective in causing uterine contractions. Oral use of misoprostol may be convenient, but high doses could cause uterine hyperstimulation and uterine rupture which may be life-threatening for both mother and fetus.

OBJECTIVES

To assess the effectiveness and safety of oral misoprostol used for labour induction in women with a viable fetus in the third trimester of pregnancy.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (January 2005).

SELECTION CRITERIA

Randomised trials comparing oral misoprostol versus other methods, placebo or no treatment, given to women with a viable fetus for labour induction.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed trial quality and extracted data, using centrally-designed data sheets.

MAIN RESULTS

Forty-one trials (8606 participants) were included. In four trials comparing oral misoprostol with placebo (474 participants), women using oral misoprostol were less likely to have long labours (relative risk (RR) 0.16, 95% confidence interval (CI) 0.05 to 0.49), needed less oxytocin (RR 0.32, 95% CI 0.24 to 0.43) and had a lower caesarean section rate (RR 0.62, 95% CI 0.40 to 0.96). In nine trials comparing oral misoprostol with vaginal dinoprostone (2627 participants), women given oral misoprostol were less likely to need a caesarean section, but this reduction reached statistical significance only in the subgroup with intact membranes (RR 0.78, 95% CI 0.66 to 0.94). Uterine hyperstimulation was more common after oral misoprostol (RR 1.63, 95% CI 1.09 to 2.44) although this was not associated with any adverse fetal events. Seven trials (1017 participants) compared oral misoprostol with intravenous oxytocin. The only difference between the groups was an increase in meconium-stained liquor in women with ruptured membranes following administration of oral misoprostol (RR 1.72, 95% 1.08 to 2.74). Sixteen trials (3645 participants) compared oral and vaginal misoprostol and found no difference in the primary outcomes. There was less uterine hyperstimulation without fetal heart rate changes in those given oral misoprostol (RR 0.37, 95% 0.23 to 0.59). Oral misoprsotol was associated with increased need for oxytocin augmentation (RR 1.28, 95% 1.11 to 1.48) and more meconium-stained liquor (RR 1.27, 1.01 to 1.60).

AUTHORS' CONCLUSIONS

Oral misoprostol appears to be more effective than placebo and at least as effective as vaginal dinoprostone. However, there remain questions about its safety because of a relatively high rate of uterine hyperstimulation and the lack of appropriate dose ranging studies. In countries where misoprostol remains unlicenced for the induction of labour, many practitioners will prefer the legal protection of using a licenced product like dinoprostone. There is no evidence that misoprostol given orally is inferior to the vaginal route and has lower rates of hyperstimulation. If misoprostol is used orally, the dose should not exceed 50 mcg.

A comparison of oral and vaginal misoprostol for induction of labor

OBJECTIVE

The aim of the study is to compare the efficacy and safety of oral (100 microg) and vaginal (50 microg) misoprostol for labor induction.

STUDY DESIGN

Ninety-nine patients with indications for labor induction randomly received 100 microg oral misoprostol every 4 h or 50 microg vaginal misoprostol every 4 h, using maximum six doses. Mean induction to delivery interval, mode of delivery, rates of tachysystole, hypertonus and hyperstimulation syndrome, oxytocin use, number of doses used, failed induction rate and neonatal outcomes were compared for the two groups.

RESULTS

Mean dose of misoprostol used for oral and vaginal misoprostol groups were 2.17+/-1.35 and 1.91+/-0.94, respectively (p=0.65). There were two failed inductions in the oral (4%) and one failed induction (2.5%) in the vaginal group after a total of six doses of misoprostol (p=0.58). There was no significant difference for the mean induction to delivery interval, to the beginning of active phase interval, active phase duration, second stage duration and the number of women who received oxytocin for induction or augmentation between the two groups (p>0.05). There were also no significant differences for intrapartum complications and neonatal outcomes between the oral and vaginal misoprostol groups (p>0.05).

CONCLUSION

Our findings indicate that, in a closely supervised hospital setting with adequate monitoring, 100 microg oral misoprostol has the potential to induce labor as safely and effectively as its 50 microg vaginal analogue. As oral use of the drug is easier for both the patient and the doctor, oral misoprostol will probably be more preferable than the vaginal route.

Oral, vaginal and sublingual misoprostol for induction of labor

OBJECTIVE

To evaluate the effectiveness and safety of different administration routes of misoprostol for induction of labor.

METHOD

PubMed, Cochrane Library and EMBASE searches were carried out using the keywords oral, vaginal, sublingual, buccal, misoprostol, labor induction, identifying randomized case-controlled trials comparing different routes for giving misoprostol to induce labor, published in English between 1994 and 2004.

RESULTS

Seventeen studies (3549 participants) were included. Compared to vaginal administration, oral misoprostol was associated with higher failure rates for achieving vaginal delivery within 24 h (odds ratio (OR) 1.61, 95% confidence interval (CI) 1.23-2.10), higher rates of uterine hyperstimulation without fetal heart rate (FHR) changes (OR 2.21, 95% CI 1.12-4.34) and lower cesarean section rates (OR 0.74, 95% CI 0.56-0.97). A lower dose of oral misoprostol (50 microg) compared to the 25-50 microg administered vaginally was associated with a higher rate of vaginal delivery not being achieved within 24 h (OR 3.60, 95% CI 2.10-6.18), more need for oxytocin augmentation (OR 2.19, 95% CI 1.65-2.92), less uterine hyperstimulation both without FHR changes (OR 0.58, 95% CI 0.42-0.80) and with FHR changes (OR 0.34, 95% CI 0.17-0.67) and fewer cesarean sections (OR 0.69, 95% CI 0.51-0.91). Compared to vaginal administration, buccal misoprostol resulted in a higher rate of failure to achieve vaginal delivery after 24 h, more frequent uterine hyperstimulation and lower rates of cesarean section, but these differences were not significant. When 50 mug of misoprostol used sublingually was compared to oral administration, the sublingual misoprostol was associated with less failure to achieve vaginal delivery after 24 h, less oxytocin augmentation and reduced cesarean section, but none of the differences were statistically significant.

CONCLUSIONS

Vaginal misoprostol appears more effective than the equivalent dosage administered orally. However, the vaginal route appears to be associated with a higher risk of uterine hyperstimulation. Sublingual misoprostol seems an effective route of administration, but a lack of data necessitates more clinical trials to establish the effectiveness and safety of the buccal/sublingual route.

Sublingual misoprostol for labor induction: a randomized clinical trial

OBJECTIVE

To compare the effectiveness of 50 microg compared with 100 microg of repetitive misoprostol dosages administered sublingually for labor induction.

METHODS

Two hundred twelve women who presented with an indication for cervical ripening and labor induction were randomly assigned to 50 microg or 100 microg of misoprostol tablets administered sublingually with double masking of treatment group dose allocation. The primary outcome was the interval from start of induction to vaginal delivery.

RESULTS

Among the 203 evaluable participants, 102 were randomly assigned to the 50-microg group and 101 to the 100-microg group. The proportion of patients who delivered vaginally in less than 12 hours and less than 24 hours was significantly higher in the 100-microg group: 28% and 63% in the 100-microg group compared with 15% and 36% in the 50-microg group, respectively (P = .01 and P = .001). The incidence of tachysystole was significantly higher in the 100-microg group (P = .02). The incidence of hyperstimulation syndrome was higher in the 100-microg group, but not statistically significant (P = .46). With respect to the proportion of patients delivered after a single dose, mode of delivery, and perinatal outcome, no significant differences between treatment groups were observed. Regarding the need for oxytocin augmentation, 61% required augmentation in the 100-microg group compared with 81% in the 50-microg group (P = .002).

CONCLUSION

One hundred micrograms of sublingual misoprostol is more effective than 50 microg of sublingual misoprostol, but is associated with a higher incidence of tachysystole and uterine hyperstimulation syndrome.

LEVEL OF EVIDENCE

I.

Prospective randomized clinical trial of inpatient cervical ripening with stepwise oral misoprostol vs vaginal misoprostol

OBJECTIVE

The purpose of this study was to compare the efficacy and safety of stepwise oral misoprostol vs vaginal misoprostol for cervical ripening before induction of labor.

STUDY DESIGN

Two hundred and four women between 32 to 42 weeks of gestation with an unfavorable cervix (Bishop score < or = 6) and an indication for labor induction were randomized to receive oral or vaginal misoprostol every 4 hours up to 4 doses. The oral misoprostol group received 50 microg initially followed by 100 microg in each subsequent dose. The vaginal group received 25 microg in each dose. The primary outcome was the interval from first misoprostol dose to delivery. Patient satisfaction and side effects were assessed by surveys completed after delivery.

RESULTS

Ninety-three (45.6%) women received oral misoprostol; 111 (54.4%) received vaginal misoprostol. There was no difference in the average interval from the first dose of misoprostol to delivery in the oral (21.1 + 7.9 hrs) and vaginal (21.5 + 11.0 hrs, P = NS) misoprostol groups. The incidence of hyperstimulation in the oral group was 2.2% vs 5.4% in the vaginal group, P = NS. Eighteen patients in the oral group (19.4%) and 36 (32.4%) in the vaginal group underwent cesarean section (P < .05). This difference was attributed to better tolerance of more doses of misoprostol by the women in the oral group. There was no difference in side effects (nausea, vomiting, diarrhea, shivering) between groups. Fourteen percent of women in the vaginal group versus 7.5% in the oral group were dissatisfied with the use of misoprostol (P = NS).

CONCLUSION

Stepwise oral misoprostol (50 microg followed by 100 microg) appears to be as effective as vaginal misoprostol (25 microg) for cervical ripening with a low incidence of hyperstimulation, no increase in side effects, a high rate of patient satisfaction, and is associated with a lower cesarean section rate.

The vagina as a route for systemic drug delivery

Exhaustive efforts have been made toward the administration of drugs, via alternative routes, that are poorly absorbed after the oral administration. The vagina as a route of drug delivery has been known since ancient times. In recent years, the vaginal route has been rediscovered as a potential route for systemic delivery of peptides and other therapeutically important macromolecules. However, successful delivery of drugs through the vagina remains a challenge, primarily due to the poor absorption across the vaginal epithelium. The rate and extent of drug absorption after intravaginal administration may vary depending on formulation factors, vaginal physiology, age of the patient and menstrual cycle. Suppositories, creams, gels, tablets and vaginal rings are commonly used vaginal drug delivery systems. The purpose of this communication is to provide the reader with a summary of advances made in the field of vaginal drug delivery. This report, therefore, summarizes various vaginal drug delivery systems with an introduction to vaginal physiology and factors affecting drug absorption from the vaginal route.

Comparison of oral and vaginal misoprostol for induction of labor at term: A randomized controlled trial

OBJECTIVE

To compare the efficacy of oral with vaginal misoprostol for induction of labor at term.

METHODS

One hundred and fifty-three pregnant women at term with indications for induction of labor and Bishop score < or = 6 were randomly assigned to receive misoprostol either 100 microg orally or 50 microg vaginally every 6 h for 48 h. Repeated doses were given until Bishop score > or = 8 was achieved or spontaneous rupture of membranes occurred. Those who were not in labor after 48 h had labor induced with amniotomy and oxytocin. The main outcome measure was induction to delivery time.

RESULTS

The median induction to vaginal delivery time in the oral group (14.3 h) was not significantly different from that of the vaginal group (15.8 h). The median number of doses was also not significantly different in the oral group compared with the vaginal group. There was a significant higher incidence of uterine tachysystole in the vaginal group compared to the oral group (17.1% vs 5.3%, P = 0.032). There was no hyperstimulation in either group. There were no significant differences between the groups with respect to oxytocin augmentation, cesarean section rate, analgesic requirement, and neonatal outcomes.

CONCLUSION

Oral administration of 100 microg misoprostol has similar efficacy to intravaginal administration of 50 microg misoprostol for labor induction with less frequent abnormal uterine contractility. 100 microg of misoprostol orally can be used as an alternative to the vaginal route for labor induction.

Cervical ripening with oral misoprostol at term

OBJECTIVES

To determine the efficacy of 200 microg single dose oral misoprostol as a cervical priming agent at term.

METHODS

In this double-blind randomized trial, 156 pregnant women requiring induction of labor with gestational age of 37-42 weeks and Bishop score < or =5, were randomized to receive either 200 microg of misoprostol or a placebo, orally. Labor was induced with intravenous oxytocin infusion 12 h after oral medication if the patient did not go into labor. The primary outcome was the change in the Bishop score 12 h after oral medication. The secondary outcomes were the timings starting from the drug administration to the onset of uterine activity, interval between oral medication and delivery, oxytocin need for induction, mode of delivery, frequency of side effects, and neonatal and maternal outcome. The chi-square or Fisher exact test, Student's t-test, and Mann-Whitney U-test were used for analysis of the data.

RESULTS

There were no significant differences in maternal characteristics or indications of induction. The Bishop score 12 h after oral medication significantly improved in the misoprostol group compared with the control group [55 (70%)>8 vs. 4 (5%)>8; P<0.001]. The induction rate was significantly reduced in the misoprostol group (P<0.001). The interval between oral medication and the onset of uterine activity was significantly shorter in the misoprostol group (P<0.001). The interval between oral medication and delivery was also significantly shorter in the misoprostol group (P<0.001). The cesarean delivery rate was significantly lower in the misoprostol group (P<0.001). There were no differences between the groups with respect to the incidence of tachysystole, hyperstimulation, adverse neonatal or maternal outcome.

CONCLUSIONS

Oral administration of 200 microg single dose of misoprostol is an effective agent not only for cervical priming but also for induction of labor at term. Furthermore, it reduces the rate of cesarean deliveries.

Six hourly vaginal misoprostol versus intracervical dinoprostone for cervical ripening and labor induction

AIM

Prospective clinical trials were conducted to assess the safety and efficacy of 6-hourly vaginal misoprostol versus intracervical dinoprostone for induction of labor.

METHODS

A total of 120 pregnant women requiring induction of labor were recruited. Cases were randomized to receive either 50 microg vaginal misoprostol 6 hourly (group 1, n = 60) or 0.5 mg intracervical dinoprostone 6 hourly (group II, n = 60). Outcome measures, such as change in Bishop's score, need of oxytocin, induction delivery interval; complications like tachysystoly, hyperstimulation, abnormal fetal heart rate, and meconium passage were compared between two groups. Statistical analysis was performed by Wilcoxan's Rank sum and Student's t-test.

RESULTS

Bishop score rise, after 6 h of initiation of therapy was significantly higher in the misoprostol group than dinoprostone, 2.98 +/- 2.57 versus 2.05 +/- 1.83 (P = 0.04). The need of oxytocin augmentation was reduced in misoprostol versus dinoprostone group, 16.6% versus 78.3% (P = <0.001). Induction delivery interval was shorter in misoprostol; 12.8 +/- 6.4 h versus 18.53 +/- 8.5 h in dinoprostone group (P = <0.01). One case (1.6%) in misoprostol group, but none in dinoprostone had tachystole (P = 1.00). Abnormal heart rate pattern was found more in misoprostol than dinoprostone 16.6% versus 4.9% (P = 0.14) and so was the incidence of cesarean section, 26.6 versus 15%, respectively (P = 0.47). Meconium passage was the same in both groups, 10% in each group.

CONCLUSION

Vaginal misoprostol 50 microg 6-hourly is safe and effective for induction of labor with lesser need of oxytocin augmentation and shorter induction delivery interval.

Oral misoprostol or vaginal dinoprostone for labor induction: a randomized controlled trial

OBJECTIVE

The objective of the study was to compare the effectiveness, safety, and side effects of low-dose oral misoprostol with vaginal dinoprostone for cervical ripening and labor induction.

STUDY DESIGN

Women with Bishop score 6 or less admitted for labor induction at term were eligible for this randomized controlled trial. Exclusion criteria were multiple pregnancy, breech, fetal distress, or previous uterine scar. The allocation to the oral misoprostol group (20 microg given every 2 hours increased to 40 microg depending on uterine contractions) or to the vaginal dinoprostone group (2 mg twice, 6 hours apart) was contained in a sealed, opaque, and consecutively numbered envelope.

RESULTS

Two hundred women (100 in each group) were included. The proportion of vaginal delivery within 24 hours was 56% in the misoprostol group and 62% in the dinoprostone group (relative risk 0.90, 95% CI 0.72-1.14). The risk of cesarean section was 18% and 19%, respectively. The median interval to delivery, calculated from survival analysis, was longer in the misoprostol group (1305 minutes) compared with the dinoprostone group (1080 minutes). The log-rank test was not significant (P =.35). Uterine hyperstimulation occurred in 9% of women in the misoprostol group compared with 14% in the dinoprostone group (P =.27). The only significant difference in neonatal outcomes was a more frequent presence of thick meconium in the misoprostol group (P =.03).

CONCLUSION

We found no difference in terms of effectiveness and safety between low-dose oral misoprostol and vaginal dinoprostone used for induction of labor. This regimen avoids the excessive uterine contractility noted in previous studies, where higher doses of misoprostol were administered at longer intervals.