Randomized trial of two doses of the prostaglandin E1 analog misoprostol for labor induction

Optimal misoprostol dosing among patients with a body mass index greater than 30: a randomized controlled trial

BACKGROUND

Patients with obesity experience an increased duration of labor with an increased risk for perinatal morbidity. When compared with parturients without obesity, they also experience fewer uterine contractions after administration of misoprostol. It is unclear if the same dose of misoprostol should be used for induction of labor in patients with obesity compared to non-obese patients. Therefore, we sought to investigate if a higher dose of misoprostol for patients with obesity is more effective.

OBJECTIVE

This study aimed to determine if 50 μg compared with 25 μg of vaginal misoprostol reduced the time from induction start to delivery among patients with obesity.

STUDY DESIGN

We performed a double-blinded, pragmatic randomized controlled trial, between June 1, 2022, and July 17, 2023. Patients with a body mass index ≥30 kg/m2 who underwent labor induction at ≥ 36 weeks' gestation, had a singleton gestation, and a cervical dilation ≤3 cm at admission were included. Patients were excluded if they had a contraindication to vaginal delivery or misoprostol administration. Patients were randomized to 25 or 50 μg of vaginal misoprostol, stratified by parity, body mass index <40 kg/m2 or ≥40 kg/m2, and provider intent to use mechanical dilation at the onset of labor induction. Usual labor management was followed at the discretion of the provider. The primary outcome was time from induction to delivery. A priori, we estimated that 90 subjects per group (N=180) were needed for an 85% power to detect a 3-hour difference between groups with a type I error of 5%. Analysis was by intention-to-treat. A 2-sample t test was used for the primary outcome, Cohen's d was used as a measure of effect, and P values were reported.

RESULTS

Of the 180 patients randomized, 88 were assigned to the 25 μg group and 92 were assigned to the 50 μg group. Of those, 96.1% of patients received the designated intervention. The baseline characteristics were similar between groups. No difference was found in the primary outcome of time to delivery (21.6 hours vs 18.6 hours; d=.28; 95% confidence interval, -0.02 to 0.57). In a planned subgroup analysis, multiparous patients delivered faster in the 50 μg group (15.2 hours vs 12.0 hours; d=.51; 95% confidence interval, 0.04-0.97). The risk for tachysystole associated with fetal heart tracing changes was rare overall (2.2%) and not significantly different between groups. No differences in maternal or neonatal adverse effects were observed.

CONCLUSION

Patients with obesity who underwent cervical ripening with 50 μg of vaginal misoprostol experienced a similar time to delivery when compared with those who received 25 μg of misoprostol. However, multiparous patients had a significantly reduced time to delivery when 50 μg was used. A higher dose of misoprostol may be a promising intervention for reducing time in labor, which warrants further study.

Safety and efficacy of titrated oral misoprostol solution versus vaginal dinoprostone for induction of labor: A single-center randomized control trial

Objective

To compare the efficacy and safety of the hourly administration of titrated oral misoprostol solution (OMS) and vaginal dinoprostone for induction of labor.

Methods

Titrated OMS was administrated hourly for induction of labor, starting with a dose of 20 µg and terminating at a dose of 50 µg. The safety and efficacy of OMS were compared with that of vaginal dinoprostone for induction of labor.

Results

From June 2016 to October 2019, 2280 (78.3%) and 2115 (72.9%) women who received titrated OMS and vaginal dinoprostone, respectively, had a vaginal delivery (P = 0.005). Cesarean delivery was performed in 632 (21.7%) and 783 (27.0%) women who received titrated OMS and vaginal dinoprostone, respectively (P = 0.008). Tachysystole with changes in fetal heart rate (FHR) was seen in 104 (3.6%) and 249 (8.6%) women in the OMS and dinoprostone groups, respectively (P = 0.007). The frequency of non‐reassuring FHR was lower in the OMS group compared to the dinoprostone group (P = 0.006).

Conclusion

The titrated OMS has an efficacy comparable to vaginal dinoprostone. Moreover, it causes a lower incidence of cesarean delivery, lower frequency of tachysystole with changes in FHR, and non‐reassuring FHR.

Titrated oral misoprostol has a similar efficacy to dinoprostone, but with a lower incidence of cesarean delivery and lower frequency of non‐reassuring fetal heart rate.

Misoprostol combined with cervical single or double balloon catheters versus misoprostol alone for labor induction of singleton pregnancies: a meta-analysis of randomized trials

Objective: To compare the effect of misoprostol combined with a cervical single or double-balloon catheter versus misoprostol alone for labor induction of singleton pregnancies with an unfavorable cervix.Methods: Systematic review and meta-analysis of randomized controlled trials (RCTs) regarding the comparison of two schemes for labor induction of singleton cephalic pregnancies with a Bishop score ≤7 and no contraindication for vaginal delivery. Six research databases were searched for articles published in all languages up to 10 May 2018 comparing misoprostol (oral or vaginal) in combination with a cervical placed single or double balloon catheter versus misoprostol treatment alone. Random effects models and inverse variance were used for meta-analyses. Summary measures were mean differences (MDs) and risk ratios (RRs) with 95% confidence interval (CI). Risk of bias was evaluated with the Cochrane tool and publication bias was assessed with Begg's and Egger's tests.Results: Fifteen RCTs reported predefined outcomes. Pooled analyses showed that the combined treatment (misoprostol + catheter) was associated with a shorter induction to delivery time interval (MD = -1.99 hours; 95% CI: -3.42, -0.56); in addition to fewer uterine hyperstimulations (RR = 0.39; 95% CI: 0.23, 0.67) and Neonatal Intensive Care Unit (NICU) admissions (RR = 0.75; 95% CI: 0.58, 0.97) as compared to misoprostol alone. There were no significant differences in RRs for tachysystole, chorioamnionitis, cesarean delivery rate, birthweight, and Apgar score at 5 minutes.Conclusion: The combined use of misoprostol and a cervical balloon catheter reduces the intervention to delivery time interval and number of NICU admissions in women induced with an unfavorable cervix.

Labor Induction Techniques: Which Is the Best?

Induction of labor is a common procedure undertaken whenever the benefits of prompt delivery outweigh the risks of expectant management. Cervical assessment is essential to determine the optimal approach. Indication for induction, clinical presentation and history, safety, cost, and patient preference may factor into the selection of methods. For the unfavorable cervix, several pharmacologic and mechanical methods are available, each with associated advantages and disadvantages. In women with a favorable cervix, combined use of amniotomy and intravenous oxytocin is generally the most effective approach. The goal of labor induction is to ensure the best possible outcome for mother and newborn.

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 between vaginal and sublingual misoprostol 50 µg for cervical ripening prior to induction of labor: randomized clinical trial

OBJECTIVE

To compare the effectiveness and safety of sublingual versus vaginal misoprostol on improving the Bishop score after 6 h of administration.

METHODS

Randomized clinical trial which includes pregnant women in gestational ages from 32/0 to 41/6, with indication of induction of labor with misoprostol. Bishop score was assessed at the time of induction and 6 h after administration of 50 µg misoprostol. Analysis was made over difference in mean Bishop score of 2 points, using a standard deviation of 2, with 90% power, reaching a 95% confidence interval.

RESULTS

102 patients were studied, 51 received sublingual misoprostol, and 51 received vaginal misoprostol. There was a statistically significant difference in cervical modifications in global terms regardless of the administration route at 6 h (P < 0.05). When analyzing each group, there was no significant difference for the mean and standard deviation for Bishop score for sublingual and vaginal route (P = 0.761). There was no significant difference in terms of mode of delivery, Apgar score, cord pH, nor in the presence of complications.

CONCLUSION

There is no statistically significant difference in terms of administration route for cervical ripening using misoprostol 50 µg, whether it was sublingual or vaginal.

TRIAL REGISTRATION NUMBER

NCT02732522. Registry website: https://clinicaltrials.gov/ .

Comparative evaluation of 50 microgram oral misoprostol and 25 microgram intravaginal misoprostol for induction of labour at term: a randomized trial

OBJECTIVES

To assess and compare the efficacy and safety of 50 µg oral misoprostol and 25 µg intravaginal misoprostol for induction of labour at term.

METHODS

This non-blinded, randomized clinical trial included 228 pregnant women at term with obstetric or medical indications for induction of labour. Women either took 50 µg misoprostol orally (two 25 µg tablets) or had one 25 µg tablet of misoprostol inserted in the posterior vaginal fornix. In each group, misoprostol administration was repeated every four hours in the same dose until regular uterine contractions were established or to a maximum of five doses. Time to delivery and outcome data for each group were compared.

RESULTS

Of the 228 women, eight (3.5%) were excluded from the analysis as they withdrew their consent after randomization. Mean induction-to-delivery interval was similar in both groups (21.22 hours in the oral group vs. 20.15 hours in the vaginal group; P = 0.58). There was no significant difference between the groups with respect to the number of women who delivered within 24 hours or who required oxytocin augmentation of labour, the mode of delivery, and neonatal outcomes (P > 0.05). Uterine hyperstimulation occurred in two women who received misoprostol vaginally, but not in any of the women in the oral misoprostol group.

CONCLUSION

Oral misoprostol in a dose of 50 µg every four hours, to a maximum of five doses, has the potential to induce labour as safely and effectively as 25 µg misoprostol administered vaginally every four hours.

Prediction of successful labor induction using transvaginal sonographic cervical measurements

PURPOSE

To predict the success of labor induction by sonographic cervical measurements, maternal/obstetrical factors, and the Bishop's score.

METHODS

Between February 2008 and February 2010, 190 consecutive pregnant women underwent clinical examination to assess the Bishop's score and transvaginal sonographic cervical measurements (cervical length, fetal head stage, and cervical dilatation) before labor induction. The following outcomes were analyzed: overall vaginal delivery and vaginal delivery up to 24 hours after labor induction.

RESULTS

Overall vaginal delivery occurred in 133 (70.0%) patients and vaginal delivery 24 hours after labor induction happened in 119 (62.6%) patients. The sonographic cervical measurements were significantly associated with all outcomes (p < 0.01). The areas under the ROC curve (AUC) of all ultrasound cervical parameters to predict the two events were 68.9% and 72.0% (cervical length); 71.6% and 73.6% (fetal head stage); and 72.0% and 73.4% (cervical dilatation). Mathematical equations were obtained to calculate the probability for each event considering the sonographic cervical measurements in association with clinical factors after regression analysis, which increased the AUC for both events (80.1% and 79.3%).

CONCLUSIONS

Transvaginal sonographic cervical measurements can predict the successful labor induction, especially when associated to clinical analysis (Bishop's score).

INDUCTION OF LABOUR WITH MISOPROSTOL - A PROSTAGLANDIN E1 ANALOGUE

The purpose of our study was to compare the safety and efficacy of intravaginal misoprostol versus existing hospital protocol of intracervical dinoprostone and oxytocin for cervical ripening and induction of labour. 200 patients with indication for induction of labour were randomly assigned to receive either intravaginal misoprostol or dinoprostone/oxytocin combination. In first group twenty five micrograms of misoprostol was placed intravaginally every 6 hours till the patient reached active stage of labour. In second group dinoprostone gel 0.5 mg was placed in the endocervix at night and oxytocin induction was started in the early morning. The average interval from start to induction of vaginal delivery was shorter in misoprostol group (1315±811 minutes) compared to dinoprostone/oxytocin group (1512±712 minutes) (p < 0.01). There was no significant difference in route of delivery. 18% of misoprostol treated patients and 23% of dinoprostone/oxytocin treated patients required Caesarean section. Complications such as uterine tachysystole were significantly higher in misoprostol group (p < 0.01) but it was not associated with increased incidence of uterine hyperstimulation. Perinatal outcome was similar in both groups.

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.

Vaginal misoprostol induction of labour: a Nigerian hospital experience

We reviewed our experience with vaginal misoprostol induction of labour in 339 consecutive women with a live fetus and intact fetal membrane using 100 mcg 12-hourly until labour was established. The labours were monitored using the WHO partograph protocol. Two hundred and sixty-five women had a successful induction while 74 had an emergency caesarean section because of cephalopelvic disproportion (63.5%), fetal distress (14.9%), prolonged labour (12.2%), antepartum haemorrhage (6.8%) and other indications (2.8%). The induction delivery interval among the women who had successful induction ranged from 3 hours 42 minutes to 26 hours 15 minutes with a mean of 9 hours 23 minutes (SD 2 hours 41 minutes). Most (73.6%) of these patients delivered within 12 hours of starting induction, the majority (95.3%) requiring only 100 mcg to go into established labour. Complications recorded in this series include fetal distress in 32 (9.4%), postpartum haemorrhage in 23 (6.8%), hyperstimulation in six (1.8%), uterine rupture in one (0.3%), birth asphyxia in eight (2.5%), admission in neonatal intensive care ward in five (1.5%), neonatal death in one (0.3%) and maternal death in one (0.3%) patient. In conclusion, misoprostol was found not only to be efficacious but relatively safe in comparison to other methods of induction in use in our hospital.

Vaginal Misoprostol Administration for Cervical Ripening and Labor Induction

Intravaginal misoprostol has been shown to be an effective agent for cervical ripening and induction of labor. Vaginal application of misoprostol has been reported in over 9000 women worldwide and seems to have safety profile similar to that of endocervically and intravaginally administered dinoprostone. Concern arises with the use of higher doses of intravaginal misoprostol (50 mcg or more) and the association with uterine contractile abnormalities and for this reason, use of low-dose misoprostol regimen has been recommended by the American College of Obstetricians and Gynecologists. The recommendation is use of a 25-mcg dose of misoprostol inserted into the posterior vaginal fornix and repeated every 3 to 6 hours as needed. Misoprostol administration to women with prior cesarean births seems to increase the likelihood of uterine scar disruption and should not be used in these women. There are reports of uterine rupture in women with unscarred uteri treated with vaginally applied misoprostol. Therefore, all patients need to be monitored adequately after misoprostol administration. Although there is a growing body of data regarding the ambulatory use of intravaginal misoprostol for cervical ripening, its use for this purpose cannot be recommended outside of investigational protocols at this time because of concerns for maternal and neonatal safety.

Induction of labor

The rate of labor induction continues to rise significantly in the United States because of a growing use of labor induction for postterm pregnancies and elective induction of labor. Although different types and doses of prostaglandins used for cervical ripening often initiate uterine activity, the principal role of these agents is to soften the unripe cervix independent of uterine activity. Several systematic reviews with meta-analyses have shown that prostaglandins are superior to placebo and oxytocin alone in ripening of the cervix. Numerous studies and meta-analyses have assessed misoprostol's efficacy and safety as a labor induction agent. The most appropriate dose and route of administration has not yet been confirmed.

A randomised controlled trial comparing low dose vaginal misoprostol and dinoprostone vaginal gel for inducing labour at term

OBJECTIVE

To compare the efficacy of low dose vaginal misoprostol and dinoprostone vaginal gel for induction of labour at term.

DESIGN

A single-blind randomised controlled trial.

SETTING

Antenatal and labour ward of a UK district general hospital.

PARTICIPANTS

Two hundred and sixty-eight women requiring induction of labour at term (>37 weeks of gestation) with no significant fetal or medical condition, no previous uterine surgery and no contraindication to prostaglandin.

METHODS

Misoprostol 25 microg (one-quarter of a 100 microg tablet) was inserted into the posterior vaginal fornix every 4 hours (to a maximum of six doses) or dinoprostone vaginal gel 1-2 mg 6 hourly (maximum of 3 mg in 24 hours).

MAIN OUTCOME MEASURE

Induction-to-vaginal delivery interval.

SECONDARY OUTCOME MEASURES

Requirements for oxytocin, mode of delivery, number of women delivering < 24 hours, incidence of uterine contraction abnormalities, incidence of abnormal cardiotocograph (CTG) recordings, 5-minute Apgar scores, umbilical cord pH recordings, analgesia requirements, admission to NICU and blood loss at delivery.

RESULTS

There were no significant differences between the two groups in induction-to-vaginal delivery interval, mode of delivery, number of women delivering within 24 hours and neonatal outcomes. The incidence of uterine contraction abnormalities (tachysystole and hyperstimulation) and the incidence of abnormal CTG recordings were also similar for both groups.

CONCLUSION

Low dose vaginal misoprostol is as effective as dinoprostone gel for inducing labour at term. There would be substantial cost savings, estimated at around 3.9 million UK pounds per annum, for maternity services if low dose misoprostol became the agent of choice for inducing labour in the UK.

A randomised comparison of oral misoprostol and vaginal prostaglandin E2 tablets in labour induction at term

OBJECTIVE

To compare the efficacy of 100 microg of oral misoprostol with 3 mg prostaglandin E2 vaginal tablets in term labour induction.

DESIGN

A non-blinded, randomised, controlled trial.

SETTING

A tertiary level, teaching Scottish Hospital.

POPULATION

Two hundred women at term with indications for labour induction and modified Bishop's cervical score of less than 8.

METHODS

The women were randomly allocated to receive either 100 microg of misoprostol orally (which could be repeated 4 hourly to a maximum of five doses if indicated), or a 3 mg tablet of prostaglandin E2 vaginally (which could be repeated in 6 hours, according to routine departmental protocol).

MAIN OUTCOME MEASURE

The number delivering vaginally within 24 hours of the induction.

RESULTS

Seventy-five women delivered vaginally in the misoprostol group and 73 in the PGE2 group. Of these, 50.7% in the misoprostol group and 54.8% in the PGE2 group delivered within 24 hours of the induction (RR 0.92, 95% CI 0.7 to 1.3). More women in the misoprostol group were given oxytocin, but this was not statistically significant (60%vs 47%, RR 1.3, 95% CI 0.98 to 1.7). Two women in the misoprostol group had uterine hyperstimulation. The neonatal outcomes were not significantly different in the two groups. There was a pound 1100 saving on direct drug costs in the misoprostol group.

CONCLUSIONS

Oral misoprostol (100 microg) has similar efficacy to vaginal PGE2 tablets, and may be an option to consider for term labour induction.

Misoprostol: A Quarter Century of Use, Abuse, and Creative Misuse

Misoprostol is a prostaglandin E1 analog originally intended for use to prevent NSAID-induced gastric ulcers. However, because of its cervical ripening and uterotonic property, misoprostol has become one of the most useful drugs in obstetrics and gynecology. Misoprostol has proven to be a very convenient and flexible drug because of its formulation as a tablet that is stable and that can be administered orally, rectally, vaginally and by the sublingual route. Beginning with its abuse for illegal abortion in the late 1980s, misoprostol has quickly become established as one of the most effective drugs for terminating pregnancies in the first and second trimesters, as well as for inducing labor in the third trimester. Its use for routine prevention of postpartum hemorrhage has not been so successful, partly as the high doses required for this indication often result in troublesome side effects. Despite the large body of medical evidence about its efficacy and relative safety, the use of misoprostol in pregnant women remained off-label until the spring of 2002.

A randomised trial comparing low dose vaginal misoprostol and dinoprostone for labour induction

OBJECTIVE

To compare vaginal misoprostol with dinoprostone for induction of labour.

DESIGN

Randomised multicentre trial.

SETTING

Labour wards of one university hospital and two teaching hospitals.

POPULATION

Six hundred and eighty-one women with indication for labour induction at >or=36 weeks of gestation, singleton pregnancy and no previous ceasarean section.

METHODS

Misoprostol (25 mcg, hospital-prepared capsule) in the posterior vaginal fornix, every four hours, maximum three times daily or dinoprostone gel (1 mg) every four hours. Oxytocin was administered if necessary.

MAIN OUTCOME MEASURES

Primary: 'adverse neonatal outcome' (5-minute Apgar score <7 and/or umbilical cord pH <7.15). Secondary: labour duration, mode of delivery and patient satisfaction.

RESULTS

Three hundred and forty-one women received misoprostol and 340 dinoprostone. The median induction-delivery interval was longer in the misoprostol group compared with the dinoprostone group (25 versus 19 hours, P= 0.008). The caesarean section rate was lower in the misoprostol group: 16.1%versus 21%, but this difference was not statistically significant RR = 0.8 (95% CI 0.6-1.04). 'Adverse neonatal outcome' was found to be similar in both groups: 21% in the misoprostol and 23% in the dinoprostone groups. Significantly fewer neonates were admitted to NICU in the misoprostol group compared with dinoprostone 19%versus 26% (RR = 0.7, 95% CI 0.5-0.98).

CONCLUSIONS

Misoprostol in this dosing regimen is a safe method of labour induction. NICU admission rates were lower in the misoprostol group. No difference could be detected in patient satisfaction between groups.

Our Experience with Vaginal Prostaglandin-E2 for Induction of Labor in Qatar: Six Months Review

In order to review our experience with prostaglandin-E2 for the induction of labour and to evaluate its safety and outcomesa retrospective study was carried out at the Women's Hospital, Hamad Medical Corporation, over a six-month period. Three hundred and thirty four patients (7% of total deliveries) were induced by PGE2 (Dinoprostone), including 105 (30%) nulliparae and 229 (70%) multiparae. Patients with a history of one previous lower segment caesarean section were also included. Post date pregnancy and diabetes were the most common indications for induction.

There were significant differences in the two groups regarding the number of doses and the mean total dose of PGE2 used. The need for syntocinon augmentation was more in the nulliparae (41% vs 22%). Failed induction occurred only in nulliparae. The rate of caesarean section in induced labour remained significantly low compared with a spontaneous labour (11.6% vs 10.7%). The caesarean section rate was higher in the nulliparae (16.0% vs 9.6%) but this was not statistically significant. The caesarean section rate was higher when Bishop score 0-4 (76% vs 24%). Only two of the babies in the study group had an Apgar score less than 7 at 5 minutes. There was one caesarean hysterectomy because of postpartum hemorrhage associated with the PGE2 induction.

Conclusion: The calculated induction rate with PGE2 was 7% of total deliveries. Induction of labour with PGE2 in a grandmultiparae and previous caesarean section is relatively safe but further multicentre studies are needed to confirm our findings.

Labor induction post-term with 25 micrograms vs. 50 micrograms of intravaginal misoprostol

OBJECTIVES

To compare the effectiveness of 25 microg vs. 50 microg of intravaginal misoprostol for cervical ripening and labor induction beyond 41 weeks' gestation.

METHODS

The study population consisted of 120 women not in active labor with a gestational age >41 weeks, singleton pregnancy with vertex presentation, reactive fetal heart rate tracing, amniotic fluid index >/=5, and Bishop score <5. Women were randomized to receive either 25 microg (n=60) or 50 microg (n=60) of intravaginal misoprostol. The dose was repeated every 4 h (maximum number of doses limited to six) until the patient exhibited three contractions in 10 min. The main outcome measure was the induction-vaginal delivery interval.

RESULTS

There was no significant difference between the two groups with regard to the induction-vaginal delivery interval (685+/-201 min in the 25 microg group vs. 627+/-177 min in the 50 microg group, P=0.09). The proportion of women delivering vaginally with one dose of vaginal misoprostol was significantly greater in the 50 microg group (0/49 vs. 41/47, P<0.001). There were no differences in the rates of cesarean and operative vaginal delivery rates, or in the incidences of tachysystole and hyperstimulation syndrome in the two treatment groups. Neonatal outcomes were also similar.

CONCLUSIONS

Intravaginal administration of 25 microg of misoprostol appears to be as effective as 50 microg for cervical ripening and labor induction beyond 41 weeks' gestation.

Misoprostol and dinoprostone therapy for labor induction: a Doppler comparison of uterine and fetal hemodynamic effects

OBJECTIVE

To compare the effect of misoprostol (PGE(1)) versus dinoprostone (PGE(2)) on blood flow in uteroplacental circulation during labor induction.

STUDY DESIGN

Eighty-four women with indications for induction of labor were assigned to receive either misoprostol 50 microg per vagina every 4 h as needed or 0.5 mg doses of dinoprostone given intra-cervically every 6 h by means of a randomization table generated by computer. Doppler velocimetry of umbilical, uterine and arcuate arteries was performed immediately before and 2-3 h after the administration of misoprostol or dinoprostone. The SAS system was used to perform statistical analysis.

RESULTS

There were no significant changes of pulsatility index (PI), resistance index (RI) and systolic/diastolic (S/D) ratio in umbilical arteries after both prostaglandin compounds. Vaginal application of misoprostol significantly increased all ratios in arcuate artery and S/D ratio in uterine artery. Intra-cervically dinoprostone significantly increased PI, RI and S/D ratio in arcuate and uterine arteries.

CONCLUSIONS

Our results indicate that vaginal misoprostol and cervical dinoprostone administration increases uteroplacental resistance but does not affect umbilical blood flow. Misoprostol would be as safe and effective agent as dinoprostone for cervical ripening and labor induction.

Vaginal misoprostol for cervical ripening and induction of labour

BACKGROUND

Misoprostol (Cytotec, Searle) is a prostaglandin E1 analogue marketed for use in the prevention and treatment of peptic ulcer disease. It is inexpensive, easily stored at room temperature and has few systemic side effects. It is rapidly absorbed orally and vaginally. Although not registered for such use, misoprostol has been widely used for obstetric and gynaecological 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 trials register (October 2002), the Cochrane Controlled Trials Register (The Cochrane Library, Issue 3, 2002) and bibliographies of relevant papers.

SELECTION CRITERIA

The criteria for inclusion included the following: (1) 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; (2) random allocation to the treatment or control group; (3) adequate allocation concealment; (4) violations of allocated management not sufficient to materially affect conclusions; (5) clinically meaningful outcome measures reported; (6) data available for analysis according to the random allocation; (7) missing data insufficient to materially affect the conclusions.

DATA COLLECTION AND ANALYSIS

A strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction. The initial data extraction was done centrally, and incorporated into a series of primary reviews arranged by methods of induction of labour, following a standardised methodology. The data will be extracted from the primary reviews into a series of secondary reviews, arranged by category of woman. To avoid duplication of data in the primary reviews, the labour induction methods have been listed in a specific order, from one to 25. Each primary review includes comparisons between one of the methods (from two to 25) with only those methods above it on the list.

MAIN RESULTS

Sixty-two trials have been included. Compared to placebo, misoprostol was associated with increased cervical ripening (relative risk of unfavourable or unchanged cervix after 12 to 24 hours with misoprostol 0.09, 95% confidence interval (CI) 0.03 to 0.24). It was also associated with reduced failure to achieve vaginal delivery within 24 hours (relative risk (RR) 0.36, 95% CI 0.19 to 0.68). Uterine hyperstimulation, without fetal heart rate changes, was increased (RR 11.7 95% CI 2.78 to 49). Compared with vaginal prostaglandin E2, intracervical prostaglandin E2 and oxytocin, vaginal misoprostol labour induction 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. Compared with intracervical prostaglandin E2, unchanged or unfavourable cervix after 12 to 24 hours was less common with misoprostol. Lower doses of misoprostol compared to higher doses were associated with more need for oxytocin augmentation, less uterine hyperstimulation, with and without fetal heart rate changes, and a non-significant trend to fewer admissions to neonatal intensive care unit. Use of a gel preparation of misoprostol versus tablet was associated with less hyperstimulation and more use of oxytocin and epidural analgesia. Information on women's views is conspicuously lacking.

REVIEWER'S CONCLUSIONS

Vaginal misoprostol appears to be more effective than conventional methods of cervical ripening and labour induction. The apparent increase in uterine hyperstimulation is of concern. Doses not exceeding 25 mcg four-hourly of concern. Doses not exceeding 25 mcg four-hourly appeared to have similar effectiveness and risk of uterine hyperstimulation to conventional labour inducing methods. The studies reviewed were not large enough to exclude the possibility of rare but serious adverse events, particularly uterine rupture, which has been reported anecdotally following misoprostol use in women with and without previous caesarean section. The authors request information on cases of uterine rupture known to readers. Further research is needed to establish the ideal route of administration and dosage, and safety. Professional and governmental bodies should agree guidelines for the use of misoprostol, based on the best available evidence and local circumstances.

Oral misoprostol (100 μg) versus vaginal misoprostol (25 μg) in term labor induction: a randomized comparison

OBJECTIVE

To compare the efficacy of vaginal misoprostol (25 microg) to oral misoprostol (100 microg) in labor induction at term.

METHODS

One hundred and one women at term, with indications for labor induction and cervical Bishop's scores of less than 8, were randomly assigned to receive 100 microg of oral misoprostol or 25 microg vaginal misoprostol after random allocation. This could be repeated every 4 h to a maximum of five doses. The number delivering vaginally within 24 h of the induction was the main outcome measure.

RESULTS

Of those who delivered vaginally (74.5% in the oral group vs. 72% in the vaginal group), significantly fewer women delivered within 24 h of induction in the oral group (42.1% vs. 72.2%, RR 0.6, 95% CI 0.4-0.9), with more women receiving more than one dose (45.7% vs. 16.7%, RR 2.7, 95% CI 1.2-6.0). More women in the oral group received oxytocin (68.6% vs. 44%, RR 1.6, 95% CI 1.1-2.2), and the induction to delivery interval was shorter in the vaginal group, although this was not statistically significant [28.9 h (SD 20.2) vs. 20.6 h (SD 16.1), mean difference - 8.3 h, 95% CI - 16.8 to 0.2]. There were no differences in the modes of delivery, uterine hyperstimulation rates or in the neonatal outcomes.

CONCLUSION

Vaginal misoprostol in its currently recommended dose of 25 microg seems to be more efficacious than the 100 microg oral dose.

A benefit-risk assessment of misoprostol for cervical ripening and labour induction

Misoprostol, a prostaglandin E(1) analogue, is widely used in the US and other countries for cervical ripening and labour induction. Its use for these indications is not approved by the US Food and Drug Administration (FDA). The manufacturer of misoprostol issued a letter to American healthcare providers in August 2000, cautioning against the use of misoprostol in pregnant women and citing a lack of safety data for its use in obstetrical practice. The only FDA-approved indication in the product labelling is the treatment and prevention of intestinal ulcer disease resulting from nonsteroidal anti-inflammatory drug use. Multiple trials have proven that when applied vaginally, misoprostol is an effective agent for cervical ripening and labour induction in term pregnancy. The use of oxytocin augmentation is reduced when intravaginal misoprostol is used compared with other agents. Misoprostol use in obstetrics carries the added benefits of temperature stability at room temperature, which is unlike other prostaglandin preparations which require refrigeration or freezing, and reduced cost. However, debate continues regarding the optimal dose, dosage regimen, and route of administration. Uterine contraction abnormalities are often found in association with higher misoprostol doses (50 microg or more) given vaginally or orally. Some trials also indicate increased frequencies of meconium passage, neonatal acidaemia and caesarean delivery for fetal distress in women receiving higher doses of vaginally applied misoprostol. However, most trials fail to demonstrate a significant change in the caesarean delivery rate with the use of misoprostol, although a recent meta-analysis indicated that the use of intravaginal misoprostol is associated with a lowering of the caesarean rate when compared with pooled controls. Low-dose misoprostol (25 microg) is an effective agent for cervical ripening and labour induction when used in a judicious and cautious fashion. There are insufficient data to support the widespread use of oral misoprostol for cervical ripening and labor induction. Some trials suggest that this approach may be effective; however, the ideal dose and administration regimen have yet to be defined.

Dose variation that is associated with approximated one-quarter tablet doses of misoprostol

OBJECTIVE

The purpose of this study was to evaluate dose variation in approximated one-quarter tablet misoprostol fragments.

STUDY DESIGN

Misoprostol 100 microg tablets were weighed, separated into two lots, and quartered with a razor blade or a pill cutter. Fragments were reweighed, and the misoprostol content was determined by high-performance liquid chromatography mass spectroscopy.

RESULTS

Fragment weights varied more when a pill cutter was used (P <.0001). Fewer pill-cutter fragments than razor-cut fragments weighed within 10% of expected (24% vs 65%, P <.0001). Misoprostol content among the fragments that were determined by high-performance liquid chromatography mass spectroscopy was 103% +/- 12% of expected (range, 73%-124%). Tablet fragments that weighed >or=27.5 mg contained misoprostol in excess of 110% of expected in seven of eight fragments, although none from fragments that weighed <or=26.5 mg did. Misoprostol was evenly distributed in all fragments that were assayed.

CONCLUSION

Misoprostol is evenly distributed among tablet fragments. Accurate low-dose misoprostol cervical ripening is possible if the tablet fragments are individually weighed.

A comparison of various routes and dosages of misoprostol for cervical ripening and the induction of labor

OBJECTIVE

The purpose of this study was to compare the efficacy of different routes of misoprostol administration for cervical ripening and the induction of labor.

STUDY DESIGN

Three hundred thirty women at > or = 32 weeks gestation with a Bishop score < or = 6 and an indication for induction were randomized to 1 of 3 double-blinded groups: (1) 25 microg orally administered misoprostol plus 25 microg vaginally administered misoprostol, (2) orally administered placebo plus 25 microg vaginally administered misoprostol, or (3) 25 microg orally administered misoprostol plus vaginally administered placebo. Doses were repeated every 4 hours until onset of labor or a maximum of 12 doses were given. The primary outcome of the trial was vaginal delivery within 24 hours of the initiation of induction. Secondary outcomes were the time from induction to delivery, need for oxytocin augmentation, mode of delivery, frequency of side effects, and neonatal and maternal outcome. Analysis of variance, chi-square test, and logistic regression were used for analysis.

RESULTS

There were no significant differences in maternal characteristics or indications for induction. The percentage of women who achieved vaginal delivery within 24 hours was highest in the vaginally administered misoprostol group: 67% compared with 53% in the oral-plus-vaginal group (P < .05) and 36% in the oral group (P < .05). The median time to vaginal delivery was shorter in the vaginal and oral-plus-vaginal misoprostol groups, 13.5 hours and 14.3 hours, respectively, when compared with 23.9 hours in the oral group (P < .05). The rate of cesarean delivery was lowest in the vaginal misoprostol group (17% compared with 30% in the oral-plus-vaginal group and 32% in the oral group; P < .05). Uterine tachysystole occurred least frequently in the oral misoprostol group (10% compared with 32% in the vaginal group and 34% in the oral-plus-vaginal group; P < .05). Uterine hyperstimulation also occurred least frequently in the oral misopro-stol group (4% compared with 15% in the vaginal group and 22% in the oral-plus-vaginal group; P < .05).

CONCLUSION

At the doses studied, induction of labor with vaginally administered misoprostol is more efficacious than either oral-plus-vaginal or oral-only route of administration.

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

OBJECTIVE

To determine the efficacy of oral misoprostol (50 microg) administered every 3 hours compared to vaginal misoprostol (50 microg) administered every 6 hours for induction of labor.

STUDY DESIGN

In this double-blind randomized trial, 126 women received misoprostol (50 microg) either orally every 3 hours or vaginally every 6 hours for induction of labor. Outcomes included time from induction to delivery, oxytocin augmentation, incidence of hyperstimulation and tachysystole, mode of delivery, and neonatal outcomes.

RESULTS

Median time to delivery was shorter in those women who were receiving vaginal misoprostol (vaginal 14.3 hours vs oral 23.1 hours; P =.0004) and more women in the oral group required oxytocin augmentation of labor (73% vs 42%) (RR, 1.98; 95% CI, 1.29 to 3.06). The incidence of hyperstimulation was similar between the groups, but there was an increased incidence of tachysystole in the vaginal group (26.5% vs 9.7%)(RR, 2.74; 95% CI, 1.16 to 6.51). There was no difference between the groups with respect to mode of delivery or neonatal outcome.

CONCLUSION

Vaginal misoprostol administered every 6 hours is more effective for induction of labor than oral misoprostol administered every 3 hours. The higher rates of tachysystole with use of vaginal misoprostol in the current study warrant further investigation.

A comparison of oral and vaginal misoprostol tablets in induction of labour at term

OBJECTIVE

To compare the efficacy of equivalent doses of orally administered with vaginally administered misoprostol in induction of labour at term.

DESIGN

A non-blinded randomised controlled trial.

SETTING

Induction and labour wards of a UK teaching hospital.

PARTICIPANTS

Two hundred and forty-five pregnant women at term, with medical or obstetric indications for labour induction and unfavourable cervices.

METHODS

The women were randomly assigned to receive 50 microgm of misoprostol orally or vaginally four hourly to a maximum of five doses.

MAIN OUTCOME MEASURES

Interval from induction to vaginal delivery, mode of delivery, oxytocic and analgesic requirements in labour, neonatal outcome, patient satisfaction and acceptability.

RESULTS

The mean induction to vaginal delivery interval was significantly shorter in the vaginal group compared with the oral group (17.8h vs 27.9h: mean difference 10.1 hrs, 95% CI 5.8-14.4). More women were delivered within 24 hours (80% vs 46.3%; RR 1.7, 95% CI 1.3-2.1) and fewer women needed oxytocin augmentation (39% vs 58.2%; RR 0.67, 95% CI 0.5-0.9) in the vaginal group. There was no difference in the mode of delivery, analgesic requirements or neonatal outcomes in the two groups. There was a higher incidence of uterine hyperstimulation in the vaginal group (4.9% vs 0.8%, RR 6, 95% CI 0.07-48.7) and more caesarean sections were performed for fetal distress in this group (13% Vs 2.4%, RR 5.3, 95% CI 1.6-17.7), although the overall operative delivery rate was similar in the two groups.

CONCLUSION

Misoprostol effectively induces labour, with the vaginal route of administration having a faster action than the oral route in equivalent doses. However, the more frequent occurrence of hyperstimulation and the higher intervention rate for fetal distress in the vaginal group could mean that the preferred route might be oral. More trials are needed to find the right oral dosage that combines efficacy with safety.

Vaginal misoprostol for induction of labor: 25 vs. 50 microg dose regimen

OBJECTIVE

To compare the efficacy and safety of two regimens of vaginal misoprostol for induction of labor.

METHOD

In a randomized study, 185 women undergoing induction of labor were allocated to Group A (n=93), to be given 25 microg misoprostol and Group B (n=92), to be given 50 microg misoprostol. Intravaginal misoprostol was given every 4 h until the onset of labor. A maximum of six doses was administered.

RESULTS

Abnormal uterine contractions were more common in Group B compared to Group A: 33 (35.86%) vs. 10 (10.75%) cases, and significantly more women in Group B required tocolysis (9.78 vs. 3.23%). The induction-delivery interval (mean+/-S.D.) was 17.18+/-8.48 h in Group A and 9.37+/-5.87 h in Group B (P<0.05). Oxytocin infusion was used in 37.63% of women in Group A and 26.08% in Group B (P>0.05). The cesarean section rate was 17.20% in Group A and 14.13% in Group B (P>0.05). Cesarean for failed IOL was more common in Group A: 7 of 16 (43.8%) vs. 3 of 13 (23.1%) cesarean deliveries (P<0.05). Postpartum hemorrhage occurred in 9.78% of women in Group B compared to 2.15% in Group A (P<0.05). There was a trend for more neonatal complications in Group B, but this did not reach significance.

CONCLUSIONS

Although a dose of 50 microg of misoprostol results in a significantly shorter induction-delivery interval with less need for labor augmentation, there was an increased risk of uterine contractile abnormalities and postpartum hemorrhage. A regime using 25 microg of misoprostol every 4 h can induce labor safely and effectively.

Use of misoprostol in obstetrics and gynecology

Misoprostol is prostaglandin E1 analogous and marketed for prevention and treatment of peptic ulcer disease. However, it has been used widely in obstetrics and gynecology practice because of its effectiveness, low cost, stability in light and hot climate conditions, and ease of administration compared with its licensed counterparts--dinoprostone and gemeprost. A large number of studies have shown that misoprostol is effective in first and second trimester abortion, late pregnancy labor induction, and third stage of labor management (misoprostol has not been approved by the U.S. Food and Drug Administration for these indications). Because misoprostol is not registered for such use, it has not undergone the extensive testing for appropriate dosage and safety required for registration. Serious complications such as teratogenesis after failed abortions and uterine rupture during second trimester abortions and third trimester labor induction have been reported as the result of increasingly wide use of misoprostol in obstetric and gynecology practice. There is an urgent need to evaluate all the available data and organize a large randomized trial to determine the safety of its use in obstetric and gynecology practice.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to identify the various uses of misoprostol, to describe the potential complications of misoprostol use and its teratogenic effects, to compare the various routes of administration, and to define the appropriate dose.

Effect of vaginal pH on efficacy of misoprostol for cervical ripening and labor induction

OBJECTIVE

We sought to evaluate whether vaginal pH has an effect on the relative efficacy of misoprostol for cervical ripening and labor induction.

STUDY DESIGN

Thirty-seven gravid women with an unfavorable cervix and indication for labor induction were enrolled in this prospective, double-blind, observational study. Baseline assessments of cervicovaginal pH and Bishop score were made at the time of enrollment by an independent examiner. All patients received 50 microg misoprostol intravaginally every 6 hours for 12 hours. After the initial 12 hours of preinduction, a repeat Bishop score assessment was made by the same initial examiner. Patients not in active labor at 12 hours were placed on a standardized oxytocin induction regimen. Labor was managed by the on-call obstetric team, who remained blinded to pH assessment. Clinical outcomes were evaluated. Statistical analyses were made by the Student t test, the Fisher exact test, and linear regression analysis.

RESULTS

Average initial vaginal pH was 4.8 +/- 0.5 (range, 3.5-7.0) for the study cohort. No significant differences were noted between those patients with low vaginal pH (< or =4.5) compared with those with high pH vaginal (>4.5) with respect to maternal age, parity, gestational age, or initial Bishop score. Similarly, Bishop score change over preinduction interval (5.6 vs 4.9), time to active labor (16.3 vs 17. 1 hours), time to complete dilatation (20.0 vs 19.9 hours), and time to delivery (21.0 vs 21.6 hours) were not significantly different between the low and high pH groups, respectively. Linear regression analysis revealed no significant association between vaginal pH and Bishop score change during preinduction interval, time to active labor, time to complete dilatation, or time to delivery.

CONCLUSION

Vaginal pH does not appear to influence the efficacy of intravaginally administered misoprostol for cervical ripening and labor induction.

Uterine and fetal Doppler flow changes after misoprostol and oxytocin therapy for induction of labor in post-term pregnancies

OBJECTIVES

To compare the effect of misoprostol vs. oxytocin on blood flow in uteroplacental circulation during labor induction.

METHODS

Ninety-one women with indications for induction of labor were assigned to receive either misoprostol 50 microg per vagina every 4 h as needed or intravenous oxytocin by means of a randomization table generated by computer. Doppler velocimetry of umbilical, uterine and arcuate arteries was performed immediately before and 2-3 h after administration of misoprostol or oxytocin. Pulsatility index (PI), resistance index (RI) and systolic/diastolic (S/D) ratios were measured for these arteries. The SAS system was used to perform statistical analysis.

RESULTS

There were no significant changes of PI, RI and S/D ratios in umbilical arteries during misoprostol and oxytocin inductions. Vaginal application of misoprostol significantly increased PI, RI and S/D ratios in arcuate arteries and S/D ratio in uterine arteries.

CONCLUSIONS

Our results indicate that intravaginal misoprostol administration increases uteroplacental resistance but probably does not substantially affect placental perfusion.

Labor induction with misoprostol

Misoprostol, a prostaglandin E(1 ) analog, is widely used in the United States for cervical ripening and labor induction. Its use for these indications is not approved by the US Food and Drug Administration. The only Food and Drug Administration-approved indication in the product labeling is the treatment and prevention of intestinal ulcer disease resulting from nonsteroidal anti-inflammatory use. Multiple trials have proved that misoprostol is an effective agent for cervical ripening and labor induction in term pregnancy; however, investigations continue regarding the optimal dose, dosing regimen, and route of administration. Uterine contraction abnormalities are often found in association with higher misoprostol doses. Some trials also indicate increased frequencies of meconium passage, neonatal acidemia, and cesarean delivery for fetal distress in women receiving higher doses of misoprostol. Overall, most trials fail to demonstrate a significant change in the cesarean delivery rate with the use of this agent. Misoprostol is an effective agent for cervical ripening and labor induction when used in a judicious and cautious fashion.

Misoprostol for induction of labour at term: a more effective agent than dinoprostone vaginal gel

OBJECTIVE

To compare the efficacy of vaginal misoprostol and dinoprostone vaginal gel for induction of labour at term.

DESIGN

A single-blind randomised comparative trial.

SETTING

Induction and labour wards of a UK teaching hospital.

PARTICIPANTS

Two hundred and eleven pregnant women at term in whom induction of labour was indicated, and with no contra-indication to the use of prostaglandins for the induction of labour.

INTERVENTION

The women were randomly assigned to receive vaginal administration of either misoprostol 50 microg four hourly (to a maximum of four doses) or dinoprostone gel 1 mg six hourly (to a maximum of three doses).

MAIN OUTCOME MEASURES

Time from induction to delivery, oxytocin requirement in labour, analgesic requirement, mode of delivery, neonatal outcome.

RESULTS

The misoprostol group had a highly significant reduction in median induction-delivery interval compared with the dinoprostone group (14.4 hours vs 22.9 hours; P < 0.00001). In addition, more women delivered after only one dose (77% vs 49%; P < 0.0001, OR 3.51, 95% CI 1.94-6.35), and within 12 and 24 hours. There was a reduced need for oxytocin augmentation in labour (21% vs 47%; P < 0.0001, OR 0.30, 95% CI 0.16-0.54). There was no difference in analgesia requirement in labour, or in mode of delivery. There were no adverse neonatal outcomes associated with the use of misoprostol. Women in the misoprostol group experienced more pain in the interval between induction and being given analgesia in labour, but this did not reach statistical significance.

CONCLUSIONS

Misoprostol 50 microg vaginally is a more effective induction agent than 1 mg dinoprostone vaginal gel, with no apparent adverse effects on mode of delivery, or on the fetus. The higher pain scores in the misoprostol group must be balanced against the reduction in time spent having labour induced, and the reduction in need for intravenous oxytocin augmentation. Further randomised studies must continue to exclude the possibility of rare adverse side effects.

Misoprostol is more efficacious for labor induction than prostaglandin E2, but is it associated with more risk?

OBJECTIVE

Our purpose was to compare the efficacy and safety of misoprostol with dinoprostone (Prepidil) for labor induction.

STUDY DESIGN

In a randomized, controlled trial of labor induction, patients were randomly assigned to receive either 50 microgram of intravaginal misoprostol every 4 hours or 0.5 mg of intracervical prostaglandin E2 every 6 hours. Eligibility criteria included gestation of >/=31 weeks, Bishop score <6, and fewer than 12 contractions per hour. Primary outcomes were cesarean section, induction to delivery time, oxytocin use, and fetal distress requiring delivery.

RESULTS

One hundred fifty-nine women were randomly assigned to receive misoprostol (n = 81) or Prepidil (n = 78). There were no differences in the indication for induction, preinduction Bishop score, epidural use, or cesarean section rate. Mean time to delivery was significantly shorter in the misoprostol group (19 hours 50 minutes) than in the Prepidil group (28 hours 52 minutes) (P =.005). Only 58% of women in the misoprostol group required oxytocin augmentation, in comparison with 88% of women receiving Prepidil (P =.00002). However, 41% of women receiving misoprostol and 17% receiving Prepidil had late decelerations or bradycardias (P =.001), and 20% of the misoprostol group and 5% of the Prepidil group had deliveries for fetal distress (P =.05).

CONCLUSIONS

Misoprostol is more efficacious than Prepidil for labor induction. However, the significantly increased incidence of abnormal fetal heart rate tracings and the trend in increased deliveries for fetal distress with misoprostol dosing of 50 microgram every 4 hours are of concern. These data suggest that either a lower dose of misoprostol or less frequent dosing of misoprostol should be considered.

Comparison of the safety and efficacy of intravaginal misoprostol (prostaglandin E1) with those of dinoprostone (prostaglandin E2) for cervical ripening and induction of labor in a community hospital

OBJECTIVE

This clinical trial evaluated the efficacy of intravaginal misoprostol (prostaglandin E1) and compared it with that of dinoprostone (prostaglandin E2) for cervical ripening and induction of labor in a community hospital.

STUDY DESIGN

This study involved a retrospective analysis of 81 patients undergoing cervical ripening and induction of labor with prostaglandin E2 from May 1, 1996, to May 1, 1997. A comparison prospective analysis of 145 patients undergoing the same procedure with prostaglandin E1 from May 1, 1997 to May 1, 1998, was performed.

RESULTS

The mean time to delivery was significantly shorter with misoprostol (19.8 +/- 10.4 hours) than with prostaglandin E2 (31.3 +/- 13.0 hours, P <.001). Delivery within 24 hours of induction was significantly more frequent with misoprostol (71.9% of subjects vs 31.3%, P <.001). There was no difference in the cesarean delivery rate with misoprostol (25.6% vs 22.2%, P <.67). The incidence of uterine hyperstimulation was higher with prostaglandin E2 (7.4% vs 0.7%, P <.007). There were no uterine ruptures with prostaglandin E2. There were 2 uterine ruptures and 1 dehiscence with prostaglandin E1 in 3 patients with previous cesarean deliveries and 1 rupture in a patient without a history of uterine scarring. There was no difference in neonatal outcome, with the exception of a fetal death related to uterine rupture in the misoprostol group.

CONCLUSIONS

Compared with prostaglandin E2, misoprostol is more effective in cervical ripening and induction of labor, is as safe for patients who do not have a history of cesarean birth, may carry a higher incidence of uterine rupture, and should not be used for patients attempting vaginal birth after previous cesarean delivery.

A double-blind randomized trial of two dose regimens of misoprostol for cervical ripening and labor induction

OBJECTIVES

The objective of this study was to compare the efficacy and safety of two dosing regimens of misoprostol for cervical ripening and labor induction.

METHODS

Patients who fulfilled the study criteria were randomized to received misoprostol 25 microg or 50 microg intravaginally every 3 h for a total of eight doses for cervical ripening or until labor was established. Endpoints for successful cervical ripening was achievement of Bishop score of nine or greater, and for labor induction reaching the active phase of labor in the first 24 h. The rates of success, duration of first and second stages of labor, type of delivery, significant side effects, and neonatal outcome were measured and compared between the two study groups. Two hundred and fifty-one patients were randomized in two groups--126 received 50 microg and 125 received 25 microg misoprostol. Demographics of the two study groups were similar.

RESULTS

Patients in the 50 microg group had a shorter first stage (848 min vs. 1,122 min, P < 0.007), shorter induction-to-vaginal delivery interval (933 min vs. 1,194 min, P < 0.013), decreased incidence of oxytocin augmentation (53.9% vs. 68%, P < 0.015), and decreased total units of oxytocin (2,763 mU vs. 5,236 mU, P < 0.023), but there was a higher hyperstimulation rate (19% vs. 7.2%, P < 0.005).

CONCLUSIONS

Successful induction rate, delivery types, and fetal outcome were similar in both groups. Although the rate of vaginal delivery and neonatal outcome were similar in both groups, the 50 microg regimen had shorter first and second stages of labor, and a higher hyperstimulation rate that was easily manageable, allowing for flexibility in using the higher dose in low-risk pregnancies.

Medication use during the perinatal period

OBJECTIVE

To briefly describe the drug therapy administered during the perinatal period of pregnancy for common maternal and fetal complications, and to identify those agents that should not be used for these conditions.

DATA SOURCES

References were obtained from an ongoing literature search of peer-reviewed obstetric and gynecologic journals and other selected medical and pharmacy journals available in the English language. Primary search vehicle was a weekly review of the tables of contents of nearly 1,300 medical journals provided by Reference Update (Institute of Scientific Information, Philadelphia). MEDLINE searches were also conducted using key terms for each subtopic.

STUDY SELECTION

Specific references were selected for each topic based on the adequacy of their study design, patient population, and a recent publication date. Reviews were used if a large number of primary references would have been required to adequately describe the topic.

DATA EXTRACTION

Most references reflected the current opinions expressed in the Educational (Technical) Bulletin and Committee Opinion series published by the American College of Obstetricians and Gynecologists. Recent, well-conducted studies that arrived at different conclusions were also included.

DATA SYNTHESIS

Data obtained from each reference reflected the conclusions of the authors based on their research or an analysis of the research on others on the appropriate use of the drug(s) for the specific condition being treated.

CONCLUSION

Drug therapy during the perinatal period is frequently required and can be beneficial for the mother, fetus, and newborn. Many complications previously associated with severe morbidity and mortality, such as infections, premature rupture of membranes, preterm labor, hypertension, maternal pain during labor, and postpartum hemorrhage, are now controlled with appropriate pharmacologic therapy. All health professionals who provide services to pregnant women should be knowledgeable in this drug therapy.