The effect of vaginal administration of various doses of prostaglandin E2 gel on cervical ripening and induction of labor

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.

Vaginal prostaglandin (PGE2 and PGF2a) for induction of labour at term

BACKGROUND

Prostaglandins have been used for induction of labour since the 1960s. This is one of a series of reviews evaluating methods of induction of labour. This review focuses on prostaglandins given per vaginam, evaluating these in comparison with placebo (or expectant management) and with each other; prostaglandins (PGE2 and PGF2a); different formulations (gels, tablets, pessaries) and doses.

OBJECTIVES

To determine the effects of vaginal prostaglandins E2 and F2a for third trimester cervical ripening or induction of labour in comparison with placebo/no treatment or other vaginal prostaglandins (except misoprostol).

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 March 2014) and bibliographies of relevant papers.

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

We assessed studies and extracted data independently.

MAIN RESULTS

Seventy randomised controlled trials (RCTs) (11,487 women) are included. In this update seven new RCTs (778 women) have been added. Two of these new trials compare PGE2 with no treatment, four compare different PGE2 formulations (gels versus tablets, or sustained release pessaries) and one trial compares PGF2a with placebo. The majority of trials were at unclear risk of bias for most domains.Overall, vaginal prostaglandin E2 compared with placebo or no treatment probably reduces the likelihood of vaginal delivery not being achieved within 24 hours. The risk of uterine hyperstimulation with fetal heart rate changes is increased (4.8% versus 1.0%, risk ratio (RR) 3.16, 95% confidence interval (CI) 1.67 to 5.98, 15 trials, 1359 women). The caesarean section rate is probably reduced by about 10% (13.5% versus 14.8%, RR 0.91, 95% CI 0.81 to 1.02, 36 trials, 6599 women). The overall effect on improving maternal and fetal outcomes (across a variety of measures) is uncertain.PGE2 tablets, gels and pessaries (including sustained release preparations) appear to be as effective as each other, small differences are detected between some outcomes, but these maybe due to chance.

AUTHORS' CONCLUSIONS

Prostaglandins PGE2 probably increase the chance of vaginal delivery in 24 hours, they increase uterine hyperstimulation with fetal heart changes but do not effect or may reduce caesarean section rates. They increase the likelihood of cervical change, with no increase in operative delivery rates. PGE2 tablets, gels and pessaries appear to be as effective as each other, any differences between formulations are marginal but may be important.

Use of labour induction and risk of cesarean delivery: a systematic review and meta-analysis

BACKGROUND

Induction of labour is common, and cesarean delivery is regarded as its major complication. We conducted a systematic review and meta-analysis to investigate whether the risk of cesarean delivery is higher or lower following labour induction compared with expectant management.

METHODS

We searched 6 electronic databases for relevant articles published through April 2012 to identify randomized controlled trials (RCTs) in which labour induction was compared with placebo or expectant management among women with a viable singleton pregnancy. We assessed risk of bias and obtained data on rates of cesarean delivery. We used regression analysis techniques to explore the effect of patient characteristics, induction methods and study quality on risk of cesarean delivery.

RESULTS

We identified 157 eligible RCTs (n = 31,085). Overall, the risk of cesarean delivery was 12% lower with labour induction than with expectant management (pooled relative risk [RR] 0.88, 95% confidence interval [CI] 0.84-0.93; I(2) = 0%). The effect was significant in term and post-term gestations but not in preterm gestations. Meta-regression analysis showed that initial cervical score, indication for induction and method of induction did not alter the main result. There was a reduced risk of fetal death (RR 0.50, 95% CI 0.25-0.99; I(2) = 0%) and admission to a neonatal intensive care unit (RR 0.86, 95% CI 0.79-0.94), and no impact on maternal death (RR 1.00, 95% CI 0.10-9.57; I(2) = 0%) with labour induction.

INTERPRETATION

The risk of cesarean delivery was lower among women whose labour was induced than among those managed expectantly in term and post-term gestations. There were benefits for the fetus and no increased risk of maternal death.

Vaginal prostaglandin (PGE2 and PGF2a) for induction of labour at term

BACKGROUND

Prostaglandins have been used for induction of labour since the 1960s. Initial work focused on prostaglandin F2a as prostaglandin E2 was considered unsuitable for a number of reasons. With the development of alternative routes of administration, comparisons were made between various formulations of vaginal prostaglandins.

OBJECTIVES

To determine the effects of vaginal prostaglandins E2 and F2a for third trimester cervical ripening or induction of labour in comparison with placebo/no treatment or other vaginal prostaglandins (except misoprostol).

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2009) and bibliographies of relevant papers.

SELECTION CRITERIA

Clinical trials comparing vaginal prostaglandins 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 assessed studies and extracted data independently.

MAIN RESULTS

Sixty-three (10,441 women) have been included.Vaginal prostaglandin E2 compared with placebo or no treatment reduced the likelihood of vaginal delivery not being achieved within 24 hours (18.1% versus 98.9%, risk ratio (RR) 0.19, 95% confidence interval (CI) 0.14 to 0.25, two trials, 384 women). The risk of the cervix remaining unfavourable or unchanged was reduced (21.6% versus 40.3%, RR 0.46, 95% CI 0.35 to 0.62, five trials, 467 women); and the risk of oxytocin augmentation reduced (35.1% versus 43.8%, RR 0.83, 95% CI 0.73 to 0.94, 12 trials, 1321 women) when PGE2 was compared to placebo. There was no evidence of a difference between caesarean section rates, although the risk of uterine hyperstimulation with fetal heart rate changes was increased (4.4% versus 0.49%, RR 4.14, 95% CI 1.93 to 8.90, 14 trials, 1259 women).PGE2 tablet, gel and pessary appear to be as efficacious as each other and the use of sustained release PGE2 inserts appear to be associated with a reduction in instrumental vaginal delivery rates (9.9 % versus 19.5%, RR 0.51, 95% CI 0.35 to 0.76, NNT 10 (6.7 to 24.0), five trials, 661 women) when compared to vaginal PGE2 gel or tablet.

AUTHORS' CONCLUSIONS

PGE2 increases successful vaginal delivery rates in 24 hours and cervical favourability with no increase in operative delivery rates. Sustained release vaginal PGE2 is superior to vaginal PGE2 gel with respect to some outcomes studied.Further research is needed to assess the best vehicle for delivering vaginal prostaglandins and this should, where possible, include some examination of the cost-analysis.

Final Report on the Safety Assessment of Triacetin

Triacetin, also known as Glyceryl Triacetate, is reported to function as a cosmetic biocide, plasticizer, and solvent in cosmetic formulations, at concentrations ranging from 0.8% to 4.0%. It is a commonly used carrier for flavors and fragrances. Triacetin was affirmed as a generally recognized as safe (GRAS) human food ingredient by the Food and Drug Administration (FDA). Triacetin was not toxic to animals in acute oral or dermal exposures, nor was it toxic in short-term inhalation or parenteral studies, and subchronic feeding and inhalation studies. Triacetin was, at most, slightly irritating to guinea pig skin. However, in one study, it caused erythema, slight edema, alopecia, and desquamation, and did cause some irritation in rabbit eyes. Triacetin was not sensitizing in guinea pigs. Triacetin was not an irritant or a sensitizer in a clinical maximization study, and only very mild reactions were seen in a Duhring-chamber test using a 50% dilution. In humans, Triacetin reportedly has caused ocular irritation but no injury. Triacetin was not mutagenic. Although there were no available reproductive and developmental toxicity data, Triacetin was quickly metabolized to glycerol and acetic acid and these chemicals were not developmental toxins. Reports of 1,2-glyceryl diesters, which may be present in Triacetin, affecting cell growth and proliferation raised the possibility of hyperplasia and/or tumor promotion. The Cosmetic Ingredient Review (CIR) Expert Panel concluded, however, that the effects of 1,2-glyceryl diesters on cell growth and proliferation require longer ester chains on the glycerin backbone than are present when acetic acid is esterified with glycerin, as in Triacetin. On the basis of the available information, the CIR Expert Panel concluded that Triacetin is safe as used in cosmetic formulations.

Vaginal prostaglandin (PGE2 and PGF2a) for induction of labour at term

BACKGROUND

Prostaglandins have been used for induction of labour since the 1960s. Initial work focused on prostaglandin F2a as prostaglandin E2 was considered unsuitable for a number of reasons. With the development of alternative routes of administration, comparisons were made between various formulations of vaginal prostaglandins. 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 prostaglandins E2 and F2a for third trimester cervical ripening or induction of labour in comparison with placebo/no treatment or other vaginal prostaglandins (except misoprostol).

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group trials register (May 2003) and bibliographies of relevant papers.

SELECTION CRITERIA

Clinical trials comparing vaginal prostaglandins 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

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.

MAIN RESULTS

In total, 101 studies were considered: 43 excluded and 57 (10,039 women) included. One study is awaiting assessment. Vaginal prostaglandin E2 compared with placebo or no treatment reduced the likelihood of vaginal delivery not being achieved within 24 hours (18% versus 99%, relative risk (RR) 0.19, 95% confidence interval (CI) 0.14 to 0.25, 2 trials, 384 women), there was no evidence of a difference between caesarean section rates although the risk of uterine hyperstimulation with fetal heart rate changes was increased (4.6% versus 0.51%, RR 4.14, 95% CI 1.93 to 8.90, 13 trials, 1203 women). Comparison of vaginal prostaglandin F2a with placebo showed similar caesarean section rates but the cervical score was more likely to be improved (15% versus 60%, RR 0.25, 95% CI 0.13 to 0.49, 5 trials, 467 women), and the risk of oxytocin augmentation reduced (53.9% versus 89.1%, RR 0.60, 95% CI 0.43 to 0.84, 11 trials, 1265 women) with the use of vaginal PGF2a. There were insufficient data to make meaningful conclusions for the comparison of vaginal PGE2 and PGF2a.PGE2 tablet, gel and pessary appear to be as efficacious as each other. Lower dose regimens, as defined in the review, appear as efficacious as higher dose regimens.

REVIEWER'S CONCLUSIONS

The primary aim of this review was to examine the efficacy of vaginal prostaglandin E2 and F2a. This is reflected by an increase in successful vaginal delivery rates in 24 hours, no increase in operative delivery rates and significant improvements in cervical favourability within 24 to 48 hours. Further research is needed to quantify the cost-analysis of induction of labour with vaginal prostaglandins, with special attention to different methods of administration.

Randomized study of vaginal misoprostol (PGE(1)) and dinoprostone gel (PGE(2)) for induction of labor at term

OBJECTIVES

To investigate the efficacy and safety of misoprostol in the induction of labor at term by comparing this agent with the commonly used dinoprostone gel.

PATIENTS AND METHODS

A randomized clinical trial of vaginal misoprostol, 50 microg 6-hourly, and dinoprostone gel, 1-2 mg 6-hourly, in 435 women undergoing induction of labor at term. The women, 210 in the misoprostol group and 225 in the dinoprostone group, were compared to determine whether there was a significant difference in achieving vaginal delivery within 24 h, the incidence of hyperstimulation syndrome, Cesarean section rate and adverse neonatal outcome. They were also offered the option of preinduction sonographic cervical assessment.

RESULTS

Misoprostol, compared to dinoprostone gel, was associated with a significantly shorter median induction-to-delivery interval (14.6 h vs. 19.0 h; P = 0.0014), a higher incidence of vaginal delivery within 24 h of induction (65.7% vs. 54.2%; P = 0.019) and a reduced need for oxytocin augmentation during labor (20.5% vs. 29.8%; P = 0.034). The groups did not differ significantly in the rates of Cesarean section (18.1% vs. 19.1%; P = 0.88) and hyperstimulation syndrome (2.4% vs. 0.9%; P = 0.27). None of the cases of hyperstimulation required treatment with tocolysis. All nine cases of excessive uterine contractility occurred after the first dose of the drug. There were no significant differences in maternal and neonatal morbidity between the two groups. There was a significant association between preinduction cervical length and the induction-to-delivery interval in both those receiving misoprostol and those treated with dinoprostone.

CONCLUSIONS

The use of misoprostol is associated with a shorter duration of labor and a higher rate of vaginal delivery within 24 h from induction without an increase in maternal and neonatal morbidity. Transvaginal sonographic measurement of cervical length is useful in the prediction of the likelihood of vaginal delivery within 24 h of induction and of the induction-to-delivery interval and may be useful in the stratification of patients participating in randomized studies that examine the effectiveness of inducing agents.

Determinants of response to intracervical prostaglandin E2 for cervical ripening. Gruppo di Studio sull'Induzione del Travaglio di Parto

OBJECTIVE

To analyze the determinants of response to intracervical prostaglandin E2 (PGE2) in cervical ripening.

STUDY DESIGN

A total of 250 women with normal pregnancy, parae three or less, with intact membranes between 40 and 42 weeks of gestation and Bishop's score < or = 4 were treated with 0.5 mg PGE2 intracervical repeated after 12 hours if cervical Bishop's score was still < or = 4.

RESULTS

After the first administration of PGE2, labor was induced in 106 (42.4%) women. Nulliparae had a significant longer interval from the first PGE2 dose to delivery and more failures of treatment and caesarean sections than parae. There was a tendency towards a shorter interval between the first administration and delivery and a decrease in the frequency of treatment failures with increasing Bishop's score, but the finding was not statistically significant. No fetal or neonatal death occurred. There were eight neonates at one min and three neonates at five min with an Apgar score less than seven. There were 22 neonates admitted to Neonatal Intensive Care Unit. There were 20 cases of jaundice.

CONCLUSIONS

The study confirms that the main determinant of treatment failure with PGE2 gel in cervical ripening is nulliparity.

Second and early third trimester pregnancy termination by extra-amniotic balloon and intracervical PGE2

OBJECTIVE

The aim of the study was to investigate the efficacy and safety of an alternative modality using extra-amniotic balloon and intracervical prostaglandin (PG) E2 for termination of second and early third trimester pregnancies.

METHOD

Thirty-three pregnant women scheduled for legal termination of pregnancy at 15-32 weeks' gestation were included in the study. Each case received extra-amniotic balloon containing 500-800 ml normal saline and two PGE2 tablets inserted into the cervical canal.

RESULTS

All 33 patients achieved a successful termination. The mean induction-to-abortion interval was 12.85 h. There was no significant difference in induction-to-abortion interval between second trimester group and third trimester group. However, the mean duration of balloon distention was longer in the second trimester group. There were no severe complications.

CONCLUSION

The combined use of extra-amniotic balloon and intracervical PGE2 tablets is effective, safe and convenient for termination of second and early third trimester pregnancy.

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

OBJECTIVE

Our purpose was to compare the safety and effectiveness of intravaginally administered misoprostol at doses of 25 micrograms and 50 micrograms for indicated labor induction in patients with an unfavorable cervix.

STUDY DESIGN

Three hundred ninety-nine patients received either 25 micrograms or 50 micrograms of misoprostol, placed intravaginally in the posterior fornix, in this randomized double-blind trial. The dose was repeated every 3 hours until adequate labor was achieved (at least three contractions in 10 minutes).

RESULTS

Among 399 patients evaluated, 192 patients were allocated to the 25 micrograms group and 207 patients to the 50 micrograms group. The start-to-delivery interval was shorter in the 50 micrograms group (826 minutes vs 970 minutes, p = 0.02). The incidence of vaginal delivery after one dose was higher in the 50 micrograms group (38.2% vs 25.0%, p = 0.007). Patients receiving 25 micrograms required oxytocin augmentation more frequently than did those receiving 50 micrograms (27.1% vs 16.9%, p = 0.02). No differences were noted in the cesarean or other operative delivery rates among patients in the two treatment groups. The incidence of newborns with a cord pH < 7.16 was greater in the 50 micrograms group (13.0% vs 6.8%, p = 0.04). Although the incidence of hyperstimulation was similar between the groups, the incidence of tachysystole was higher in the 50 micrograms group (32.8% vs 15.6%, p = 0.0001).

CONCLUSIONS

Although a dose of 50 micrograms is associated with a shorter start-to-delivery interval and a higher incidence of vaginal delivery after one dose, 25 micrograms of intravaginal misoprostol is effective and associated with a lower incidence of tachysystole and cord pH values < 7.16.

Induction of labor utilizing vaginal vs. intracervical prostaglandin E2

OBJECTIVE

To compare the efficacy of intracervical vs. vaginal prostaglandin E2 (PGE2) gel for induction of labor.

METHOD

Sixty-eight women scheduled for elective induction of labor at term were randomized to receive either 0.5 mg intracervical PGE2 (I/C group, n = 37) or 2 mg vaginal PGE2 gel (Vag group, n = 31) on a 6-hourly basis for a maximum of three doses.

RESULTS

Three participants who delivered by cesarean section soon after gel administration were excluded from further analysis. Twenty-nine of 30 (97%) in the Vag group were successfully induced compared with 23 of 35 (66%) in the I/C group (P < 0.01). The induction-active labor intervals were 8.0 +/- 5.4 h for the Vag group and 23.1 +/- 27.6 h for the I/C group (P = 0.002). The induction-delivery intervals were 12.4 +/- 6.3 h for the Vag group and 29.8 +/- 29.1 h for the I/C group (P = 0.001). Uterine hyperstimulation and perinatal outcome were similar in both groups.

CONCLUSION

Vaginal PGE2 was more efficacious than intracervical PGE2 in inducing labor.

Double-blind comparison of intracervical and intravaginal prostaglandin E2 for cervical ripening and induction of labor

OBJECTIVE

Our purpose was to compare the safety and effectiveness of prostaglandin E2 delivered sequentially as an intracervical (0.5 mg) or intravaginal (2.5 mg) gel.

STUDY DESIGN

Hospitalized patients with an unfavorable cervix (Bishop score < or = 4) at > or = 35 weeks and requiring induction of labor were assigned to receive two 2.5 ml doses of gel intracervically and intravaginally in a double-blind, placebo-controlled manner. Second and third doses were given at 6-hour intervals until there were either regular uterine contractions or a Bishop score change > 3 points.

RESULTS

The 100 evaluable cases received prostaglandin E2 either intracervically (n = 52) or intravaginally (n = 48). Difficulty with exact gel instillation was present with intracervical gel only, where spillage occurred in 85% of cases. Compared with intracervical therapy prostaglandin E2 given intravaginally was more likely to significantly change the Bishop score (60.4% vs 40.4%, p = 0.04) and stimulate regular contractions (72.9% vs 48.1%, p = 0.01). Uterine hyperstimulation was present in one case in each group.

CONCLUSION

Although each was safe, instillation of prostaglandin E2 gel was better at a higher intravaginal dose than a lower intracervical dose because of its greater ease of administration and higher likelihood of cervical change.

Vaginal prostaglandins for the ripe cervix

OBJECTIVES

To assess the efficacy of vaginal prostaglandin (PGE2) tablets for induction of labor in the presence of a ripe cervix.

METHODS

A randomized controlled trial was performed. Two hundred and nine consecutive women undergoing induction of labor with a Bishop Score > or = 5 were randomly assigned to (a). Study group receiving PGE2 tablets (n = 106) and (b). Control group having artificial rupture of membranes only (n = 103). The duration of labor, oxytocin and analgesia requirements, the mode of delivery, complications and duration of confinement were recorded.

RESULTS

Mean duration of first stage of labor was shorter in parous patients in the study group (194 min v. 319 min), as was the mean induction delivery interval in primigravidas. Oxytocin was used in 75% of primiparas and 40% multiparas in the study group compared with 100% and 80%, respectively, in the controls. Epidural analgesics and instrumental delivery rates were also reduced.

CONCLUSIONS

The use of vaginal PGE2 tablets for induction of labor with a ripe cervix is associated with a shorter first stage of labor and with reduced requirements for oxytocin, analgesia and instrumental delivery.

Induction of labor with intravaginal prostaglandin E2 gel

OBJECTIVE

The aim of our study was to evaluate the optimum dose of intravaginal prostaglandin E2 gel for induction for labor in nulliparous women with a relatively ripe cervix (modified Bishop score 4 or 5).

METHOD

One hundred and sixty-seven nulliparous women at term with indications for the induction of labor were treated randomly with two doses of intravaginal 2.0 (group A) or 3.0 mg (group B) of prostaglandin PGE2 gel every 12 h. Data were analyzed by chi 2-test and Student's t-test.

RESULTS

Of 87 patients 64 went into labor after gel application in group A, compared with 68/80 in group B (73.5% vs. 85.0%) (P = NS). A second gel administration was needed for 9 women in group A and 6 women in group B. More side effects (both local and systemic) were noted in group B than in group A (28.7% vs. 14.9%) (P = 0.03). In particular, more local (hyperstimulation or hypertonus) side effects were noted in group B (13.7% vs. 2.3%) (P = 0.01).

CONCLUSION

The vaginal administration of 2.0 mg of PGE2 gel seems to be equally effective as 3.0 mg in terms of labor success rate with a significant lower incidence of side effects.

A randomized trial of 30-min and 15-min oxytocin infusion regimen for induction of labor at term in women of low parity

OBJECTIVE

To investigate in women of low parity (para 1, 2 or 3) whether induction of labor using a regimen of intravenous oxytocin, increasing incrementally at 30-min intervals is safer than one increasing at 15-min intervals.

METHOD

Two hundred and forty-five women of low parity requiring induction of labor by infusion of oxytocin were randomly allocated to incremental increases at 30-min intervals (123 women) as experimental group or 15-min intervals (122 women) as the control group. In both groups forewater amniotomy was performed synchronously with oxytocin infusion using the allocated regimen.

RESULTS

The 30-min incremental regimen resulted in less precipitate labor, uterine hyperstimulation and a reduced length of stay in hospital. The induction delivery interval was longer with the experimental group which also had less occurrence of postpartum hemorrhage, perineal tears and puerperal pyrexia.

CONCLUSION

Oxytocin infusion regimen with 30 min incremental increases is safer than the regimen with 15-min incremental increases.

Uterine rupture at term pregnancy with the use of intracervical prostaglandin E2 gel for induction of labor

Prostaglandin E2 is a powerful oxytocic agent that reliably initiates labor, even in the presence of an unripe cervix. The low incidence of fetomaternal complication contributes to its universal use. We report a rare case of uterine rupture after intracervical application of prostaglandin E2 gel. Thus far no prostaglandin compound or method of administration seems to be exempt from such a complication.

Prostaglandin E2 (PGE2) vaginal gel for cervical ripening

Cervical ripening prior to oxytocin stimulation is highly desirable to ensure a successful induction. Prostaglandin E2 has been administered by intracervical, intravaginal and extra-amniotic routes with successful ripening of the cervix. The dose of PGE2 administered is under investigation. Use of 3 or 4 mg of PGE2, although effective, has been reported to be accompanied by uterine hypertonus or fetal heart changes. Lower dose of PGE2 at 0.2 mg and 0.4 mg do not have the above-mentioned side effects but necessitate multiple applications. This randomized double-blinded study incorporated the use of 2 mg of PGE2 administered by intravaginal route in a hydroxyethyl cellulose gel medium. A significant increase in Bishop score (40% higher) was achieved in patients receiving PGE2 as compared to placebo patients. There were no adverse side effects, indicating application of 2 mg of PGE2 as a safe method of cervical ripening prior to induction of labor.

Uterine hyperstimulation after low-dose prostaglandin E2 therapy: tocolytic treatment in 181 cases

There is limited information about uterine hyperstimulation after low-dose prostaglandin E2 therapy. The purpose of this retrospective study was to describe our combined experience with this undesired effect by use of three techniques for prostaglandin E2 administration. Uterine hyperstimulation was present if the contraction frequency was more than five in 10 minutes or if contractions exceeded 2 minutes in duration. A total of 181 cases were evaluated during a 51-month period. The rates of hyperstimulation were 7.3% (167/2297) in the group that received intravaginal tablets (3.0 mg), 2.9% (12/408) with intravaginal gel (2.5 mg), and 0.5% (2/394) with intracervical gel (0.5 mg). Hyperstimulation usually began within the first hour for the group that used gel and within the first 4 hours for the tablet group. A beta 2-adrenergic drug (hexoprenaline or terbutaline) was infused routinely without adverse effects and with rapid resolution of the worrisome findings in 178 (98.3%) cases. The remaining three cases required cesarean delivery and had no evidence of neonatal compromise. We conclude from this large, combined series that uterine hyperstimulation after low-dose prostaglandin E2 therapy is uncommon and usually rapidly reversible with beta 2-adrenergic therapy without apparent untoward effects.

Double-blind comparison of intravaginal prostaglandin E2 gel and "chip" for preinduction cervical ripening

The intravaginal application of prostaglandin E2 for preinduction cervical ripening has proved to be advantageous in the management of patients with an unfavorable cervix. The purpose of this double-blind randomized investigation was to compare the efficacy and safety of two methods of prostaglandin E2 delivery. Patients who were to have preinduction cervical ripening because of an unfavorable cervix (Bishop score less than or equal to 4) were randomly assigned to be given a single dose of prostaglandin E2 as either 2.5 mg of gel or a 3.0 mg "chip" intravaginally in a placebo-controlled manner. Sixty-nine patients received the active prostaglandin E2, 34 in the gel group and 35 in the "chip" group. The groups were similar in maternal age, race, parity, gestational age, and initial Bishop score. Both forms of prostaglandin E2 were easy to administer and helpful in priming an unfavorable cervix. The need for, duration of, and maximum dose of oxytocin were similar in both groups. Cesarean delivery because of failed induction occurred in 5 of 35 (14.3%) patients receiving a "chip" and 4 of 34 (11.8%) receiving the gel. However, patients receiving a "chip" experienced a 20% (7/35) incidence of hyperstimulation, compared with 2.9% (1/36) in those receiving the gel (p less than 0.05). The only case requiring immediate cesarean delivery because of intractable uterine hyperstimulation received a "chip." We conclude that both methods were effective for cervical ripening, but the lower incidence of uterine hyperstimulation seen with the gel would suggest that it is preferable to the "chip."

Effect of intravaginal application of prostaglandin E2 gel on the mechanical properties of the ovine cervix uteri at term

The extensibility ("creep" or strain per minute) and the stretch modulus (stress per unit strain) of strips of cervical tissue were measured in vitro. Intravaginal application of prostaglandin E2 gel led to a fourfold increase in the extensibility (mean +/- SE, 15.45 +/- 0.26 versus 4.23 +/- 0.86 min-1; p less than 0.05) and a twofold reduction in the stretch modulus (mean +/- SE, 0.66 +/- 0.03 versus 1.28 +/- 0.12 N.mm2; p less than 0.0005). This marked increase in the degree of softening occurred in the absence of an increase in uterine activity or changes in plasma progesterone concentrations.

Initiation of labor with a moderately favorable cervix: a comparison between prostaglandin E2 gel and oxytocin

This study compares prostaglandin E2 (PGE2) gel and oxytocin for the initiation of labor in term pregnancies with a moderately favorable cervix (Bishop score 5-8). Compared with a matched group, 48 cases treated with PGE2 gel (2.5 mg intravaginally) required significantly less or no oxytocin, had shorter first stages of active labor, and had no increased risk of uterine hyperstimulation or cesarean section. Initiation of labor with low dose PGE2 when the cervix is moderately favorable is less labor intensive and meets with more patient satisfaction.

Prostaglandin E2 gel for cervical ripening and induction of labor: a critical analysis

This report summarizes the cumulative experience of 3313 pregnancies represented in 59 prospective clinical trials in which intracervical or intravaginal prostaglandin E2 gel was used for cervical ripening before induction of labor. Results indicate that local prostaglandin E2 is superior to placebo or no therapy in enhancing cervical effacement and dilation, reducing initial induction failures, shortening the induction-delivery interval, reducing oxytocin use, and lowering the rate of cesarean section because of failure to progress. Certain advantages also exist for labor induction in the presence of a favorable cervical state. Uterine hyperstimulation or pathologic fetal heart rate patterns before oxytocin administration occur in less than 1% of reported cases and are usually dose related, self contained, and reversible with the use of beta-adrenergic tocolytic therapy. Maternal systemic effects in these low doses are negligible. Worldwide clinical experience has clearly demonstrated that prostaglandin E2 gel administered before induction of labor is of major therapeutic benefit and should become commercially available for more than investigational use.