Misoprostol for cervical ripening and labor induction: a systematic review of the literature

Methods for the induction of labor: efficacy and safety

This review assessed the efficacy and safety of pharmacologic agents (prostaglandins, oxytocin, mifepristone, hyaluronidase, and nitric oxide donors) and mechanical methods (single- and double-balloon catheters, laminaria, membrane stripping, and amniotomy) and those generally considered under the rubric of complementary medicine (castor oil, nipple stimulation, sexual intercourse, herbal medicine, and acupuncture). A substantial body of published reports, including 2 large network meta-analyses, support the safety and efficacy of misoprostol (PGE1) when used for cervical ripening and labor induction. Misoprostol administered vaginally at doses of 50 μg has the highest probability of achieving vaginal delivery within 24 hours. Regardless of dosing, route, and schedule of administration, when used for cervical ripening and labor induction, prostaglandin E2 seems to have similar efficacy in decreasing cesarean delivery rates. Globally, although oxytocin represents the most widely used pharmacologic agent for labor induction, its effectiveness is highly dependent on parity and cervical status. Oxytocin is more effective than expectant management in inducing labor, and the efficacy of oxytocin is enhanced when combined with amniotomy. However, prostaglandins administered vaginally or intracervically are more effective in inducing labor than oxytocin. A single 200-mg oral tablet of mifepristone seems to represent the lowest effective dose for cervical ripening. The bulk of the literature assessing relaxin suggests this agent has limited benefit when used for this indication. Although intracervical injection of hyaluronidase may cause cervical ripening, the need for intracervical administration has limited the use of this agent. Concerning the vaginal administration of nitric oxide donors, including isosorbide mononitrate, isosorbide, nitroglycerin, and sodium nitroprusside, the higher incidence of side effects with these agents has limited their use. A synthetic hygroscopic cervical dilator has been found to be effective for preinduction cervical ripening. Although a pharmacologic agent may be administered after the use of the synthetic hygroscopic dilator, in an attempt to reduce the interval to vaginal delivery, concomitant use of mechanical and pharmacologic methods is being explored. Combining the use of a single-balloon catheter with dinoprostone, misoprostol, or oxytocin enhances the efficacy of these pharmacologic agents in cervical ripening and labor induction. The efficacy of single- and double-balloon catheters in cervical ripening and labor induction seems similar. To date, the combination of misoprostol with an intracervical catheter seems to be the best approach when balancing delivery times with safety. Although complementary methods are occasionally used by patients, given the lack of data documenting their efficacy and safety, these methods are rarely used in hospital settings.

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.

Meta-analysis of Foley catheter plus misoprostol versus misoprostol alone for cervical ripening

BACKGROUND

The effectiveness of Foley catheter plus misoprostol for cervical ripening has not been convincingly shown in trials.

OBJECTIVES

To summarize the evidence comparing Foley catheter plus misoprostol versus misoprostol alone for cervical ripening.

SEARCH STRATEGY

Embase, Medline, and Cochrane Collaboration databases were searched with the terms "Foley catheter," "misoprostol," "cervical ripening," and "labor induction."

SELECTION CRITERIA

Randomized controlled trials comparing the methods of cervical ripening for delivery of a viable fetus were included.

DATA COLLECTION AND ANALYSIS

Study characteristics, quality, and outcomes were recorded. Random-effects models were used to combine data.

MAIN RESULTS

Eight trials were included, with 1153 patients overall. In a pooled analysis of seven high-quality studies, the combination group had a decreased time to delivery (mean difference -2.36 hours, 95% confidence interval [CI] -4.07 to -0.66; P=0.007). Risk of chorioamnionitis was significantly increased in the combination group (risk ratio [RR] 2.07, 95% CI 1.04-4.13; P=0.04), and that of tachysystole with fetal heart rate changes was decreased (RR 0.58, 95% CI 0.38-0.91; P=0.02). Frequency of cesarean did not differ (P=0.77).

CONCLUSIONS

The combined use of Foley catheter and misoprostol results in a reduced time to delivery, a reduced frequency tachysystole with fetal heart rate changes, and an increased incidence of chorioamnionitis.

Oral misoprostol versus vaginal dinoprostone for labor induction in nulliparous women at term

OBJECTIVE

To compare the efficacy of oral misoprostol to vaginal dinoprostone for labor induction in nulliparous women.

STUDY DESIGN

Admissions for labor induction from January 2008 to December 2010 were reviewed. Patients receiving oral misoprostol were compared with those receiving vaginal dinoprostone. The primary outcome was time from induction agent administration to vaginal delivery. Secondary outcomes included vaginal delivery within 24 h, mode of delivery and maternal and fetal outcomes.

RESULT

A total of 680 women were included: 483 (71%) received vaginal dinoprostone and 197 (29%) received oral misoprostol. Women who received oral misoprostol had a shorter interval to vaginal delivery (27.2 vs 21.9 h, P<0.0001) and were more likely to deliver vaginally in <24 h (47% vs 64%, P=0.001). There was no increase in the rate of cesarean delivery or adverse maternal or neonatal outcomes.

CONCLUSION

Labor induction with oral misoprostol resulted in shorter time to vaginal delivery without increased adverse outcomes in nulliparous women.

The pharmacology of prostaglandins for induction of labor

Prostaglandin medications are frequently used in the process of induction of labor. Understanding the history and research that supports prostaglandin use for induction of labor is crucial for safe practice. Dinoprostone has been the standard of care for cervical ripening in term pregnancies. Misoprostol administration via various routes has been shown to be efficacious. Oral misoprostol in particular is effective and associated with reassuring maternal and fetal outcomes. In addition, cost has become a variable in decision making regarding best practice. More research is necessary to determine the safest medication, route, dose, and interval of administration. This article reviews cervical physiology and endogenous prostaglandin activity in relation to labor, and the pharmacologic profiles of synthetic prostaglandins currently used for induction of labor.

Prediction of successful labor induction by evaluation of maternal symptoms at an early stage of the misoprostol induction protocol

OBJECTIVE

This prospective observational study evaluated maternal symptoms and characteristics that predict successful labor induction with oral misoprostol.

METHODS

A total of 244 consecutive women undergoing labor induction voluntarily completed a questionnaire about subjective sensations and pain scores during the induction protocol. Maternal and neonatal characteristics were collected retrospectively from patient files. On the first day of induction, oral misoprostol (50 μg) every 4 h up to three doses was used.

RESULTS

A total of 46% of the parturients delivered or reached the active phase of labor 24 h after the initial dose of misoprostol (ID). In the whole study, 87% of the women delivered vaginally. In multivariable analysis, rupture of membranes, cervical dilatation before the initial dose, maternal sensation of painful contractions at 8 h after the initial dose, and gestational age, were found to be associated with successful labor induction.

CONCLUSIONS

Maternal sensation of painful contractions 8 h after an ID is an independent predictive factor of successful labor induction (defined as delivery or active phase of labor 24 h after beginning of induction). Other independent predictive factors are rupture of membranes, cervical dilatation before the initial dose, and gestational age.

A randomised controlled trial of low-dose misoprostol and dinoprostone vaginal pessaries for cervical priming

OBJECTIVE

We studied the efficacy of 25-microg misoprostol pessaries as either single or double dose compared with a 3-mg dinoprostone pessary for cervical priming.

DESIGN AND SETTING

A randomised controlled trial in Singapore.

POPULATION

One hundred and seventy-one women with term pregnancies and modified Bishop scores (mBS) < or =6 from 2003 to 2004.

METHOD

Patients were randomised to single misoprostol dose, double misoprostol dose or the current dinoprostone regimen.

MAIN OUTCOME MEASURES

Primary outcome was number of women who achieved favourable mBS >6 or active labour by day 2. Secondary outcomes were time interval from insertion to delivery, cardiotocographic abnormalities, delivery and neonatal outcome.

RESULTS

More women in the misoprostol double-dose group (96.6%) and dinoprostone group (93%) achieved the primary outcome compared with the single-dose group (77.8%) (P = 0.003 and P = 0.03, respectively). There was no difference in secondary outcomes. More multiparous women achieve primary outcome compared with nulliparous women (odds ratio 0.21, 95% confidence interval 0.06-0.77).

CONCLUSION

Double-dose misoprostol 25 microg is as effective as dinoprostone 3 mg inserts for cervical priming; both are more efficacious than a single-dose misoprostol pessary. Parity prognosticates the success of induction.

Reduction in caesarean delivery with fetal heart rate monitoring and intermittent pulse oximetry after induction of labour with misoprostol

OBJECTIVE

To integrate intermittent fetal pulse oximetry (FPO) to intrapartum fetal assessment and reduce the rate of caesarean sections.

METHODS

A randomised controlled trial using 37 weeks as a restriction point was conducted in 230 women induced with misoprostol. One hundred-fourteen were assessed with intermittent FPO plus fetal heart rate (FHR) monitoring (study group) and 116 were assessed with FHR monitoring alone (control group). The primary outcome measure was caesarean delivery rates. Secondary outcome measures included induction to delivery interval, number of emergency caesarean deliveries performed for fetal non-reassuring FHR patterns and neonatal outcomes.

RESULTS

There was a reduction both in the overall caesarean deliveries (study n = 18, (15.7%); vs. control n = 31 (26.7%); p = 0.04), and the rate of caesarean deliveries performed for non-reassuring fetal status in the study group (study n = 11, (9.6%); vs. control n = 23 (19.8%); p = 0.03). Induction to delivery interval was similar in between the groups (759 +/- 481 min in group 1; vs. 735 +/- 453 min in group 2 respectively; p = 0.69).

CONCLUSION

Intermittent FPO in misoprostol induced deliveries decreases both total caesarean rate and the caesarean rate due to non-reassuring FHR patterns.

Low-dose oral misoprostol for induction of labor: a systematic review

OBJECTIVE

To estimate the efficacy and safety of low-dose oral misoprostol compared with dinoprostone (PGE2), vaginal misoprostol, and oxytocin for labor induction in women with a viable fetus.

DATA SOURCES

We conducted electronic database searches of PubMed, MEDLINE, EMBASE, and the Cochrane Library for articles published before January 2008 using the keywords misoprostol, labor, induction, randomized controlled trials, dinoprostone, oxytocin, pregnancy, and maternal and fetal side effects.

METHODS OF STUDY SELECTION

We included randomized controlled trials comparing 20-25 micrograms oral misoprostol with vaginal misoprostol, dinoprostone or oxytocin given to women at 32-42 weeks of gestation for labor induction. From 401 citations identified, results from nine studies were finally analyzed using the Review Manager software. Relative risk (RR) and 95% confidence intervals (CIs) were calculated using fixed and random-effects models.

TABULATION, INTEGRATION, AND RESULTS

Nine articles with 2,937 women met the inclusion criteria. The five trials comparing oral misoprostol and dinoprostone showed significantly fewer women requiring cesarean delivery in the misoprostol group (20% compared with 26%; RR 0.82, 95% CI 0.71-0.96). There were no statistically significant differences in risks of uterine hyperstimulation or need for oxytocin augmentation. Two trials compared oral with vaginal low-dose misoprostol. Women using oral misoprostol were significantly less likely to experience uterine hyperstimulation with fetal heart rate changes (2% compared with 13%; RR 0.19, 95% CI 0.08-0.46), but there were no significant differences in other outcomes.

CONCLUSION

Low-dose oral misoprostol solution (20 micrograms) administered every 2 hours seems at least as effective as both vaginal dinoprostone and vaginal misoprostol, with lower rates of cesarean delivery and uterine hyperstimulation, respectively.

Vaginal Misoprostol versus high dose of oxytocin for labor induction: a comparative study

To compare the efficacy and complications of intravaginal Misoprostol with oxytocin for induction of labor this study was carried out. One hundred and ten term pregnant women with Bishop score of < or = 4 were randomized into two groups. Fifty five patients received 50 microg intravaginal Misoprostol 2 times at 6 h intervals (Misoprostol group), the second group received oxytocin infusion (6 mu min(-1)) for induction of labor (oxytocin group n = 55). The time from induction to delivery, the route of delivery, fetal outcome and maternal complications were recorded. There was no statistically significant difference regarding demographic or clinical characteristics between two groups. Induction success within the first 12 h were 80 and 33.3% for Misoprostol and oxytocin groups respectively (p<0.05). The average time from induction to delivery was 10. 6 +/- 3.7 and 17 +/- 7.2 h in the Misoprostol and oxytocin administered groups, respectively (p<0.05). The rate of vaginal delivery was significantly higher in misoprostol group (72.7%) when compared with oxytocin group (45.5%). Low Apgar score, meconium stain amniotic fluid, abnormal FHR and precipitating labor was similar in both groups (p>0.05). We concluded misoprostol 50 microg vaginally (every 6 h, up to 100 microg) safely and effectively induces labor and it is recommended for parturient women with Bishop score < or = 4 and the use of this drug could produce several beneficial effects, particularly a decrease in the incidence of cesarean delivery.

Comparative efficacy and safety of vaginal misoprostol versus dinoprostone vaginal insert in labor induction at term: a randomized trial

OBJECTIVE

To compare efficacy and safety of vaginal misoprostol (PGE(1) analog) with dinoprostone (PGE(2) analog) vaginal insert for labor induction in term pregnancies.

STUDY DESIGN

A total of 112 women with singleton pregnancies of > or =37 weeks of gestation, and low Bishop scores underwent labor induction. The subjects were randomized to receive either 50 mug misoprostol intravaginally every 4 h to a maximum of five doses or a 10 mg dinoprostone vaginal insert for a maximum of 12 h. Time interval from induction to vaginal delivery, vaginal delivery rates within 12 and 24 h, requirement of oxytocin augmentation, incidence of tachysystole and uterine hyperstimulation, mode of delivery, rate of cesarean section due to fetal distress and neonatal outcome were outcome measures. Student's t test, Chi square test, Fischer's exact test were used for statistical analysis.

RESULTS

Time interval from induction to vaginal delivery was found to be significantly shorter in misoprostol group when compared to dinoprostone subjects (680 +/- 329 min vs. 1070 +/- 435 min, P < 0.001). Vaginal delivery rates within 12 h were found to be significantly higher with misoprostol induction [n = 37 (66%) vs. n = 25 (44.6%); P = 0.02], whereas vaginal delivery rates in 24 h did not differ significantly between groups [n = 41 (73.2%) vs. n = 36 (64.2%); P = 0.3]. More subjects required oxytocin augmentation in dinoprostone group [n = 35 (62.5%) vs. n = 20 (35.7%), P = 0.005] and cardiotocography tracings revealed early decelerations occurring more frequently with misoprostol induction (10.7 vs. 0%, P = 0.03). Tachysystole and uterine hyperstimulation, mode of delivery, rate of cesarean sections due to fetal distress and adverse neonatal outcome were not demonstrated to be significantly different between groups (P = 1, P = 0.5, P = 0.4, P = 0.22, P = 0.5).

CONCLUSION

Using vaginal misoprostol is an effective way of labor induction in term pregnant women with unfavorable cervices, since it is associated with a shorter duration of labor induction and higher rates of vaginal delivery within 12 h. Misoprostol and dinoprostone are equally safe, since misoprostol did not result in a rise in maternal and neonatal morbidity, namely, tachysystole, uterine hyperstimulation, cesarean section rates and admission to neonatal intensive care units as reported previously in literature.

Prospective randomised controlled trial to compare safety and efficacy of intravaginal Misoprostol with intracervical Cerviprime for induction of labour with unfavourable cervix

A randomised prospective trial was carried out to compare the efficacy and safety of intravaginal Misoprostol with intracervical dinoprostone gel for induction of labour in cases of unfavourable cervix. One hundred women with an unfavourable cervix requiring induction of labour were randomised to receive either 25 microm vaginal Misoprostol 4-hourly or 0.5 mg of intracervical dinoprostone 12 hourly. The outcome measured was change in Bishop's score, percentage of women going into labour, induction to delivery interval, need for oxytocin, mode of delivery and complications. The parity, mean period of gestation and Bishop's score were similar in both the groups. The improvement in Bishop's score at 12 h was significantly better in the Misoprostol group. Induction to delivery interval was shorter in the Misoprostol group, 16.59 +/- 5.13 h vs 27.77 +/- 12.71 h. The rate of complications was comparable. Vaginal Misoprostol 25 microg 4-hourly is safe and effective for induction of labour with shorter induction to delivery interval.

Comparing two dinoprostone agents for cervical ripening and induction of labor: a randomized trial

OBJECTIVE

To compare dinoprostone gel and insert in achieving successful vaginal delivery in nulliparous and multiparous women.

STUDY DESIGN

220 nulliparous and 100 multiparous with a Bishop score < or =7 were randomized to receive dinoprostone either gel or insert for cervical ripening. The main outcome measures were the rate and latency of vaginal delivery.

RESULTS

In nulliparous women no significant differences were found between the gel and insert groups in the rate of vaginal delivery (85.6% vs. 80.7%) delivery < or =12 (36.8% vs. 32.9%) and < or =24h (85.3% vs. 93.4%) regardless of the preinduction Bishop score. Nulliparous with Bishop score < or =4 treated with the insert had a decreased risk (p<0.05) of post partum hemorrhage (4.8%) when compared with nulliparous treated with gel (16.7%). On the contrary, in multiparous the time to delivery interval was significantly shorter in the gel treated group (9.9+/-4.9h vs. 13.1+/-5h; p<0.001) with more patients delivering vaginally < or =12h (75% vs. 37.5%, p<0.001), regardless of the preinduction Bishop score.

CONCLUSION

Both dinoprostone gel and insert are efficient in achieving cervical ripening and successful labor in nulliparous and multiparous. In multiparous, however, the gel significantly reduces the time to vaginal delivery with more patients delivering vaginally < or =12h, regardless of the Bishop score.

Rectal Misoprostol Versus Oxytocin in the Management of the Third Stage of Labour

OBJECTIVE

To compare the effect of rectal misoprostol with intramuscular oxytocin in the routine management of the third stage in a rural developing country.

METHODS

A randomized controlled trial was performed at two district hospitals in Ghana, West Africa. Four hundred fifty women in advanced labour were enrolled. The only exclusion criterion was a known medical contraindication to prostaglandin administration. Women were randomized to receive rectal misoprostol 800 microg or intramuscular oxytocin 10 IU with delivery of the anterior shoulder. The main outcome measure was change in hemoglobin concentration from before to after delivery. Secondary outcomes included the need for additional uterotonics, estimated blood loss, transfusion, and medication side effects.

RESULTS

Demographic characteristics were similar in each treatment group. There was no significant difference between treatment groups in change in hemoglobin (misoprostol 1.19 g/dL and oxytocin 1.16 g/dL; relative difference 2.6%; 95% confidence intervals [CI]-16.8% to 19.4%; P = 0.80). The only significant secondary outcome was shivering, which was more common in the misoprostol group (misoprostol 7.5% vs. oxytocin 0.9%; relative risk 8.0; 95% CI 1.86-34.36; P = 0.001).

CONCLUSION

Rectal misoprostol 800 microg is as effective as 10 IU intramuscular oxytocin in minimizing blood loss in the third stage of labour. Rectal misoprostol has a lower incidence of side effects than the equivalent oral dose. This confirms the utility of misoprostol as a safe and effective uterotonic for use in the rural and remote areas of developing nations where other pharmacologic agents may be less feasible.

Misoprostol compared with prostaglandin E2 for labour induction in women at term with intact membranes and unfavourable cervix: a systematic review*

BACKGROUND

Misoprostol is a commonly used prostaglandin to induce labour. A potential risk of induction, however, is caesarean delivery, especially in women with an unfavourable cervix.

OBJECTIVES

To evaluate the use of misoprostol, compared with prostaglandin E2 (PgE2), for labour induction in women at term with an unfavourable cervix and intact membranes.

SEARCH STRATEGY

PubMed, Medline, EMBASE and the Cochrane Library were searched for articles published in any language from January 1987 to December 2005, using the keywords 'misoprostol', 'labour/labor' and 'induction'.

SELECTION CRITERIA

We identified randomised trials of women at term (> or =37 weeks of gestation) with intact membranes and unfavourable cervix, undergoing labour induction with misoprostol, orally, vaginally, sublingually or buccally, compared with PgE2 vaginally or intracervically.

DATA COLLECTION AND ANALYSIS

Caesarean delivery was the primary outcome, with tachysystole and hyperstimulation as secondary outcomes. The primary analysis compared any misoprostol with any PgE2 for all women, with a subgroup analysis for nulliparous women. Secondary analyses compared different routes and doses of misoprostol (oral or vaginal and 25 microgram or >25 microgram) and PgE2 (intracervical or vaginal). Relative risks (RR) and 95% confidence intervals (CI) were calculated using random effects models. Main results Fourteen of 611 articles identified met the criteria for systematic review, with three providing information for nulliparous women. There was no difference in the risk of caesarean delivery between misoprostol and PgE2 groups (RR = 0.99, 95% CI = 0.83-1.17). Any misoprostol was associated with higher risks of tachysystole and hyperstimulation compared with any PgE2 (RR = 1.86, 95% CI = 1.01-3.43 and RR = 3.71, 95% CI = 2.00-6.88, respectively). There was a higher rate of vaginal delivery within 24 hours among all vaginal deliveries with any misoprostol compared with any PgE2 (RR = 1.14, 95% CI = 1.00-1.31), and among all deliveries, a lower rate of oxytocin use (RR = 0.71, 95% CI = 0.60-0.85) but a trend towards increased meconium staining was observed (RR = 1.22, 95% CI = 0.96-1.55). The use of misoprostol at starting dosages >25 microgram had similar findings to the primary analysis. Studies of lower misoprostol dosing (starting dose of 25 microgram) did not show any differences in the outcomes of interest, but the sample size of this secondary analysis was small (304 women, 155 receiving misoprostol).

AUTHOR'S CONCLUSIONS

Although misoprostol in women at term with an unfavourable cervix and intact membranes was more effective than PgE2 in achieving vaginal delivery within 24 hours, misoprostol does not reduce the rate of caesarean delivery either in all women or in the subgroup of nulliparous women, and it increases the rates of tachysystole and hyperstimulation. Further studies of misoprostol using a starting dose of 25 microgram may be warranted.

Controlled-Release Misoprostol Vaginal Insert in Parous Women for Labor Induction

OBJECTIVE

To assess the ability of a controlled-release misoprostol vaginal insert to induce labor using dose reservoirs of 25, 50, 100, and 200 microg.

METHODS

This double-blind, dose ranging, randomized study was carried out in parous women requiring induction of labor at term. Each woman was randomly assigned to receive a single misoprostol vaginal insert that could remain in place for up to 24 hours and was removed for onset of active labor, an adverse event, or having reached 24 hours in situ. The primary outcome measure was time from insertion of the misoprostol vaginal insert to vaginal delivery of the neonate.

RESULTS

A total of 124 women participated in the study. The median time to vaginal delivery was 27.5, 19.1, 13.1, and 10.6 hours for the 25-, 50-, 100-, and 200-microg doses, respectively. The percentage of women who delivered vaginally within 12 hours was 9%, 14%, 47%, and 53% (P<.001 using the 25-microg group as the comparator) and within 24 hours was 42%, 79%, 81%, and 70% (P=.003). Uterine hyperstimulation syndrome occurred in one woman who received the 25-mug, two women who received the 100-microg, and three women who received the 200-microg dose reservoirs.

CONCLUSION

Misoprostol vaginal inserts effectively induced labor in pregnant parous women at term.

LEVEL OF EVIDENCE

I.

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.

Role of Misoprostol in Overcoming an Unsatisfactory Colposcopy: A Randomized Double-Blind Placebo-Controlled Clinical Trial

OBJECTIVE

To assess the effectiveness of vaginal misoprostol in overcoming an unsatisfactory colposcopy and to analyse the factors that might influence the response to misoprostol, i.e. age, menopausal status, duration of menopause and cervical characteristics.

STUDY DESIGN

A randomized double-blind placebo-controlled clinical trial.

METHODS

Forty patients with unsatisfactory colposcopy were recruited from the colposcopy clinic and were randomly allocated to receive either 400 microg misoprostol or similar-looking placebo tablets vaginally. Repeat colposcopy was performed after 6 h noting the side effects, if any.

RESULTS

One patient was excluded from the misoprostol group because postdrug colposcopic examination could not be done due to a technical fault. Of the 19 patients in the misoprostol group, 15 (78.9%) had satisfactory examination compared to only 6 of the 20 (30%) patients in the placebo group. This effect of misoprostol was statistically significant (p = 0.004). Misoprostol in the present study averted 3 cone biopsies and 12 endocervical curettages. The side effects of misoprostol were comparable in both groups. The slit-like external os and the posterior cervical lip as the site of unsatisfactory colposcopy had better conversion rates compared to pinhole os (66.6 vs.81.2%) and anterior lip involvement (85.7 vs.100%).

CONCLUSION

Four hundred micrograms of intravaginal misoprostol is an effective and safe method to convert an unsatisfactory colposcopy into a satisfactory one.

Oral Misoprostol Versus Oxytocin in the Management of the Third Stage of Labour

OBJECTIVE

To compare the effects of oral misoprostol 800 mug with intramuscular oxytocin 10 IU in routine management of the third stage of labour.

METHODS

This randomized controlled trial was performed in a rural district hospital in Ghana, West Africa, and enrolled women in labour with anticipated vaginal delivery and no known medical contraindication to prostaglandin administration. Women were randomized to receive oral misoprostol 800 mug or intramuscular oxytocin 10 IU. Blood samples were taken to determine hemoglobin concentration before delivery and at 12 hours post partum. Treatment was administered at delivery of the anterior shoulder. The primary outcome was the change in hemoglobin concentration from before to after delivery. Secondary outcomes included other measures of blood loss and presumed medication side effects.

RESULTS

In total, 450 women were enrolled in the study. Their baseline characteristics were similar. There was no significant difference between the groups in the change in hemoglobin concentration (misoprostol 1.07 g/dL and oxytocin 1.00 g/dL). The only significant secondary outcomes were shivering (80.7% with misoprostol vs. 3.6% with oxytocin) and pyrexia (11.4% with misoprostol, none with oxytocin).

CONCLUSION

Routine use of oral misoprostol 800 microg appears to be as effective as 10 IU parenteral oxytocin in minimizing blood loss during the third stage of labour, as determined by change in hemoglobin concentration. Misoprostol appears to be a safe, inexpensive, and effective uterotonic for use in rural and remote areas, where intravenous oxytocin may be unavailable.

Misoprostol dose selection in a controlled-release vaginal insert for induction of labor in nulliparous women

OBJECTIVE

The purpose of this study was to identify the maximum tolerable dose and to determine the efficacy of different misoprostol dose reservoirs in an intravaginal controlled-release hydrogel polymer.

STUDY DESIGN

Nulliparous women at > or = 37 weeks' gestation requiring cervical ripening and induction of labor were treated with misoprostol in a controlled-release, retrievable hydrogel polymer vaginal insert. Sequential cohorts of 6 patients were to be treated with escalating dose reservoirs of 25, 50, 100, 200, and 300 mug. The insert was to be removed upon onset of active labor, at 24 hours, or earlier if treatment-related adverse events occurred. The safety end point was determination of the maximum tolerable dose (MTD) based on occurrence of hyperstimulation syndrome. Our primary efficacy end point was time to vaginal delivery.

RESULTS

Increasing reservoir doses of misoprostol up to 100 microg produced more rapid increases in modified Bishop scores, less need for oxytocin, and a shorter time to vaginal delivery. Doses above 100 microg did not further enhance cervical ripening or shorten time to vaginal delivery. The median time to vaginal delivery was 14.2 hours using the 100 microg dose. Uterine hyperstimulation and adverse fetal heart rate effects occurred with the 200 and 300 microg inserts.

CONCLUSION

The 100 microg vaginal insert resulted in successful cervical ripening and rapid vaginal delivery with an acceptable safety profile for future randomized clinical trials.

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.

Misoprostol 50 μg Sublingually versus Vaginally for Labor Induction at Term: A Randomized Study

OBJECTIVE

To compare the efficacy of misoprostol 50 mug vaginally and 50 mug sublingually for labor induction at term.

MATERIALS AND METHODS

One hundred and sixty women were randomized to receive misoprostol 50 microg vaginally (n = 80) or 50 microg sublingually misoprostol (n = 80). The doses were given every 4 h (maximum 6 doses). Primary outcome measure was number of cesarean deliveries. Induction to delivery time, delivery within 24 h, the number of misoprostol doses given; the need for oxytocin augmentation, tachysystole and uterine hyperstimulation rates and neonatal outcomes were secondary outcome measures.

RESULTS

The mean induction to delivery time was 748 +/- 379 min in the vaginal group and 711 +/- 425 in the sublingual group (p = 0.56). The number of women delivering within 24 h was 73 (91.3%) in the vaginal group and 74 (92.5%) in the sublingual group (p = 0.78). The mean number of misoprostol doses required was significantly higher in the sublingual group (1.9 +/- 1.2) compared with the vaginal group (1.1 +/- 0.4; p < 0.001). More women in the sublingual group experienced tachysystole (n = 14, 17.5%) compared with the vaginal group (n = 3, 3.8%; p = 0.005). Seven cases (8.8%) in the vaginal group and 12 cases in the sublingual group (15%) required emergent cesarean delivery for fetal heart rate abnormalities (p = 0.22). Other neonatal outcomes including umbilical artery pH, Apgar scores and intensive care unit admission were similar in the two groups.

CONCLUSION

Sublingual misoprostol is as efficacious as vaginal misoprostol for induction of labor. More frequent tachysystole is observed with misoprostol 50 microg sublingually, but neonatal outcomes are similar.

Cardiotocographic abnormalities associated with dinoprostone and misoprostol cervical ripening

OBJECTIVE

To characterize the frequency and timing of cardiotocographic abnormalities associated with the use of 3 commercially available prostaglandin analogues, misoprostol, dinoprostone gel, and dinoprostone pessary, as labor preinduction agents.

METHODS

One-hundred and eleven women undergoing induction of labor with an unfavorable cervix were randomized to receive either misoprostol 50 microg every 6 hours x 2 doses, dinoprostone gel 0.5 mg every 6 hours x 2 doses, or dinoprostone pessary 10 mg x 1 dose for 12 hours intravaginally. Oxytocin induction was initiated per standardized protocol. Cardiotocographic tracings were blindly reviewed, with abnormalities coded using established definitions.

RESULTS

Fifty-five percent of women treated with misoprostol demonstrated an abnormal tracing event within the initial 24 hours of induction, compared with 21.1% with dinoprostone pessary and 31.4% with the dinoprostone gel. The mean (+/- standard deviation) number of abnormal events was significantly greater in women treated with misoprostol (5.0 +/- 5.9) versus the dinoprostone pessary (1.6 +/- 2.5) and gel (2.2 +/- 3.1) (P < .05). In addition, these events occurred earlier after initial misoprostol dosing (5.0 +/- 4.0 hours), compared with the dinoprostone pessary (9.4 +/- 5.6 hours) and gel (7.7 +/- 6.6). Thirty-nine percent of the misoprostol-treated women had abnormal patterns within 6 hours of initial dosing, compared with those treated with the dinoprostone pessary (7.9%) and gel (17.1%).

CONCLUSION

Cardiotocographic abnormalities are more frequent after misoprostol administration compared with the dinoprostone analogues. The early onset and frequent nature of the tracing abnormalities associated with misoprostol raises concern for the potential use of misoprostol for outpatient cervical ripening.

Oral misoprostol versus intracervical dinoprostone for induction of labor

OBJECTIVES

To compare oral misoprostol with dinoprostone for induction of labor and their effects on the fetal heart rate patterns.

METHODS

In a randomized controlled trial, 200 patients received either misoprostol 50 mug orally for every 4 h, or dinoprostone 0.5 mg intracervically for every 6 h. Cardiotocographic recordings, in 10-min windows 30, 60, and 80 min after prostaglandin administration during induction and continuously during labor, were compared between the two groups. Primary outcome for effectiveness and safety was assessed in terms of the number of vaginal deliveries within 24 h and fetal heart rate abnormalities during induction and labor respectively.

RESULTS

Data from 96 patients in the misoprostol group and 95 in the dinoprostone group were analyzed. There were no significant differences in respect of the number of vaginal deliveries within 24 h (RR 1.12; 95% CI 0.88-1.42). The frequency of suspicious and pathological fetal heart rate patterns did not differ significantly but significantly more cardiotocographs in the dinoprostone group had non-reassuring baseline variability 60 min after dose administration (RR 0.33; 95% CI 0.14-0.77). Maternal and neonatal outcomes did not differ significantly.

CONCLUSION

Oral misoprostol is as effective as intracervical dinoprostone for induction of labor with no difference in the frequency of fetal heart rate abnormalities.

Unsucessful labour induction in women with unfavourable cervical scores: predictors and management

BACKGROUND

Misoprostol fails to induce labour in 5-20% of women at term.

AIM

To analyse possible predictors of unsuccessful induction with 50 microg vaginal misoprostol and effectiveness and the safety of intracervical Foley catheter application in induction failures.

METHODS

An observational study was conducted on 1030 women with singleton, live fetuses, vertex presentation, > 34 weeks of gestation and Bishop score < 5. Induction of labour with 50 microg vaginal misoprostol repeated every 6 h was attempted. Women without regular uterine contractions and cervical changes at the end of 24 h were considered to be unsuccessful, and a transcervical Foley balloon catheter was placed and inflated with 50 mL saline. Possible predictors of induction failures were analysed via logistic regression analysis. Neonatal outcomes and vaginal delivery achieved after Foley catheter were also determined.

RESULTS

Induction was successful in 918 cases (89.1%) and Foley catheter was placed in 112 (10.8%) women. Increasing gestational age in weeks (odds ratio [OR] 0.77, 95% confidence interval [CI] 0.68-0.88) and increasing Bishop score (OR 0.73, 95% CI 0.60-0.90) decreased the risk of failed induction. Failure rates were 16% (27/169) in post-term nulliparous women with Bishop score </= 1 and 40% (4/10) in preterm women with Bishop score </= 1. Foley catheter achieved vaginal delivery in 83% of these women without causing an increase in the adverse neonatal outcomes.

CONCLUSION

When misoprostol induction fails, Foley catheter is a safe and effective method for cervical ripening. Foley catheter can be the first treatment of choice in post-term nulliparous women or preterm women with Bishop score </= 1.

Uterine rupture associated with misoprostol labor induction in women with previous cesarean delivery

OBJECTIVE

To review our experience with uterine rupture in patients undergoing a trial of labor with a history of previous cesarean delivery in which labor was induced with misoprostol.

STUDY DESIGN

A retrospective chart review was used to select patients who underwent induction of labor with misoprostol during the period from February 1999 to June 2002. Women with a history of cesarean delivery were retrospectively compared with those without uterine scarring.

RESULTS

Uterine rupture occurred in 4 of 41 patients with previous cesarean delivery who had labor induced with misoprostol. The rate of uterine rupture (9.7%) was significantly higher in patients with a previous cesarean delivery (P<0.001). No uterine rupture occurred in 50 patients without uterine scarring. Women with a history of cesarean delivery were more likely to have oxytocin augmentation than those without uterine scarring (41% versus 20%; P=0.037).

CONCLUSION

Misoprostol induction of labor increases the risk of uterine rupture in women with a history of cesarean delivery.

Misoprostol for Cervical Ripening and Labor Induction in Pregnancies with Oligohydramnios

The efficacy and safety of misoprostol for cervical ripening and labor induction in patients with oligohydramnios was investigated. 57 pregnancies with oligohydramnios and 58 cases with a normal amniotic fluid volume (controls) were enrolled in this prospective trial. All patients received 50 microg of intravaginal misoprostol every 5 h. Primary outcomes were: cesarean section rate; induction to delivery time; oxytocin augmentation; uterine hyperstimulation; meconium passage; fetal heart rate (FHR) changes; fetal distress requiring delivery, and Apgar scores. There were no differences in the mean time to delivery, cesarean section rate, oxytocin augmentation or Apgar scores. The mean induction to delivery time in oligohydramnios and control groups were, 11 h 43 min and 11 h 18 min, respectively (p > 0.05). FHR changes were observed in 26.3% of oligohydramnios group and 32.7% of control group (p > 0.05). There was no statistically significant difference in the cesarean section rate and the uterine hyperstimulation between the 2 groups. These data suggest that misoprostol can be used as an effective agent for cervical ripening and labor induction in pregnancies with oligohydramnios without increasing the risk for perinatal outcome, compared to those with normal amniotic fluid volumes.

Prediction of adverse outcome associated with vaginal misoprostol for labor induction

OBJECTIVE

To identify predictors of adverse outcome in pregnant women at term receiving 50 microg of intravaginal misoprostol for labor induction.

STUDY DESIGN

A prospective observational study was conducted of 720 pregnant women at term with an unfavorable cervix and a medical or obstetric indication for labor induction. All patients received 50 microg of intravaginal misoprostol every 4h up to three doses. The primary outcome measure was "adverse outcome" defined as: neonatal death, fetal acidemia and emergent cesarean delivery performed for non-reassuring fetal heart rate tracings. A stepwise logistic regression analysis was used to identify predictors of adverse outcome.

RESULTS

Tachysystole (frequent uterine contractions) (odds ratio (OR), 3.7; 95% confidence interval (CI), 1.2-10.8) and fetal tachycardia (OR, 4.8; 95% CI, 1.4-16.2) were determined as significant predictors of adverse outcome. The specificity of the model was 94.2%, whereas the sensitivity was 20.4%.

CONCLUSION

In the absence of tachysystole and fetal tachycardia, an uneventful delivery might be expected for women receiving 50 microg of intravaginal misoprostol.

Induction of labour with a favourable cervix and/or pre-labour rupture of membranes

Premature rupture of membranes (PROM) occurs in 8% of term deliveries. In this situation labour induction with prostaglandins, compared with expectant management, results in a reduced risk of chorioamnionitis, neonatal antibiotic therapy, neonatal intensive care (NICU) admission, and increased maternal satisfaction. The use of prostaglandin is associated with an increased rate of diarrhoea and use of analgesia/anaesthesia. Compared with oxytocin, prostaglandin induction results in a lower rate of epidural use and internal fetal heart rate monitoring but a greater risk of chorioamnionitis, nausea, vomiting, more vaginal examinations, neonatal antibiotic therapy, NICU admission and neonatal infection. Women should be informed of the risks and benefits of each method of induction.Misoprostol is gaining increasing interest as an alternative induction agent. It appears to be an effective method of labour induction with term PROM. Further research is needed to identify the preferred dosage, route and interval of administration, and to assess uncommon maternal and neonatal outcomes. There has been limited research on the use of prostaglandins, including misoprostol, for induction of labour with a favourable cervix and intact membranes. Compared with intravenous oxytocin (with and without amniotomy), labour induction using vaginal prostaglandins in women with a favourable cervix (with and without PROM) results in a higher rate of vaginal delivery within 24 hours and increased maternal satisfaction. In women with a favourable cervix, artificial rupture of membranes followed by oral misoprostol has similar time to vaginal delivery compared with artificial rupture of membranes followed by oxytocin. Further research with prostaglandins, including misoprostol, is needed to evaluate other maternal and neonatal outcomes in women being induced with a favourable cervix. No form of prostaglandin induction in women with PROM or favourable cervix has proven clearly superior to oxytocin infusion.

Induction of labour with an unfavourable cervix

Labour induction is undertaken when the advantages for the mother and/or the baby are considered to outweigh the disadvantages. When the uterine cervix is unfavourable, oxytocin, with or without amniotomy, is frequently ineffective. Vaginal prostaglandin E(2) is most commonly used if it is affordable. Evidence regarding many alternative methods is discussed in this chapter. Of particular interest are misoprostol and extra-amniotic saline infusion.Misoprostol, an orally active prostaglandin E(1) analogue, has been used widely by the vaginal and oral routes for labour induction at or near term. Several recent trials have confirmed that it is highly effective. Overall Caesarean section rates appear to be reduced, despite a relative increase in Caesarean sections for fetal heart rate abnormalities. Concern remains regarding increased rates of uterine hyperstimulation and meconium-stained amniotic fluid, although data on perinatal outcome have been reassuring. Postpartum haemorrhage may be increased following labour induction with misoprostol, and isolated reports of uterine rupture, with or without previous Caesarean section, have appeared. Using small dosages appears to reduce adverse outcomes. Very large trials are needed to evaluate rare adverse outcomes.Extra-amniotic saline infusion is an effective method which appears to reduce the risk of uterine hyperstimulation that occurs with the use of exogenous uterotonics.

The MisoPROM study: A multicenter randomized comparison of oral misoprostol and oxytocin for premature rupture of membranes at term

OBJECTIVE

This study was undertaken to determine whether induction of labor with oral misoprostol will result in fewer cesarean deliveries than intravenous oxytocin in nulliparous women with premature rupture of membranes at term.

STUDY DESIGN

Three hundred five women at 10 centers were randomly assigned to receive oral misoprostol, 100 microg every 6 hours to a maximum of two doses or intravenous oxytocin. The primary outcome measure was cesarean deliveries. Secondary outcomes were time from induction to vaginal delivery and measures of maternal and neonatal safety.

RESULTS

The study was stopped prematurely because of recruitment difficulties. We present the results for the 305 enrolled women. There was no difference in the proportion of women who underwent cesarean delivery (20.1% in the misoprostol group, 19.9% in the oxytocin group). The time interval from induction to vaginal delivery was also similar (11.9 hours for the misoprostol group, and 11.8 hours for the oxytocin group). Maternal and neonatal safety outcomes were similar for the two treatments. More infants born to women in the misoprostol group received intravenous antibiotics in the neonatal period (16.4% vs 6.9%, P=.01), although there were no differences in chorioamnionitis or in proven neonatal infections. Women receiving misoprostol were less likely to have postpartum hemorrhage than those receiving oxytocin (1.9% vs 6.2%, P=.05).

CONCLUSION

Oral misoprostol does not offer any advantage in time from induction to vaginal delivery or risk of cesarean section.

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.

Comparative efficacy and cost of the prostaglandin analogs dinoprostone and misoprostol as labor preinduction agents

OBJECTIVE

The purpose of this study was to compare the relative efficacy and cost of three commercially available prostaglandin analogs, misoprostol (Cytotec), dinoprostone gel (Prepidil), and dinoprostone insert (Cervidil), as labor preinduction agents.

STUDY DESIGN

One-hundred eleven women with an unfavorable cervix who underwent labor induction were assigned randomly to receive either misoprostol 50 microg every 6 hours for two doses, dinoprostone gel 0.5 mg every 6 hours for two doses, or dinoprostone insert 10 mg for one dose intravaginally. Twelve hours later, oxytocin induction was initiated per standardized protocol. Efficacy and cost of the labor preinduction/induction with the study treatments were compared.

RESULTS

Mean Bishop score change (+/-SD) over the initial 12-hour interval was significantly greater in the misoprostol group (5.2 +/- 3.1) compared with the dinoprostone insert (3.2 +/- 2.3) or the dinoprostone gel groups (2.2 +/- 1.3, P <.0001). The proportion of women who reached complete dilation (68.4%, 50.0%, 51.4%, respectively; P =.14) and who were delivered (60.5%, 47.4%, 40.0%, respectively; P =.10) within 24 hours of the initiation of induction were not significantly different between the misoprostol, dinoprostone insert, and dinoprostone gel groups. Induction-to-delivery intervals, however, were significantly shorter among women who treated with misoprostol (24.0 +/- 10.8 hours) compared with either the dinoprostone gel (31.6 +/- 13.4 hours) or the dinoprostone insert (32.2 +/- 14.7 hours, P <.05). Overall mean cost per patient that was incurred by labor induction was significantly less for the misoprostol group ($1036.13) compared with the dinoprostone insert group ($1565.72) or the dinoprostone gel group ($1572.92, P <.0001). No significant differences were noted with respect to the mode of delivery or to the adverse maternal/neonatal outcome.

CONCLUSION

Misoprostol is more cost-effective than the comparable commercial dinoprostone prostaglandin preparations as an adjuvant to labor induction in women with an unfavorable cervix.

No benefit, but increased harm from high dose (100 microg) misoprostol for induction of labour: a randomised trial of high vs. low (50 microg) dose misoprostol

Misoprostrol, a synthetic analogue of prostaglandin E(1), has been used for cervical preparation. Its ideal dose, route and frequency of administration are still under investigation. We conducted a randomised controlled trial, in a tertiary hospital in a developing country, to compare misoprostol 50 microg (low) and 100 microg (high) for effectiveness and safety in induction of labour at term. Women admitted for induction of labour with a singleton live fetus in cephalic presentation after 37 weeks' gestation were recruited. A misoprostol tablet was inserted in the posterior vaginal fornix at 8-hour intervals. Main outcomes were duration of induction, maternal and fetal complications. The mean duration of induction was 15.4 (SD 10.6) and 14.2 (SD 13.6) h in the low- and high-groups respectively (P = 0.095). There was no difference in need for augmentation with oxytocin (OR 0.82; 95% Cl 0.36-1.86) or operative delivery (OR 1.29; 95% CI 0.26-6.84). There were two uterine ruptures and four intrapartum stillbirths in the high misoprostol group. There was no difference in postpartum haemorrhage, 9.5% vs. 7.9% (P = 1.00) and admissions to the neonatal unit 18.8% vs. 17.0% (P = 0.980) in the 1ow- and high-groups) respectively. Misoprostol 50 microg was as effective as the 100 microg dose for induction of labour whereas the higher dose had an increased risk of serious complications.

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.

Cervical ripening and induction of labor with misoprostol, dinoprostone gel, and a Foley catheter: a randomized trial of 3 techniques

OBJECTIVE

The purpose of this study was to compare the efficacy of 3 different techniques of cervical ripening and induction.

STUDY DESIGN

Patients who required cervical ripening and induction were randomized to one of 3 groups: (1) supracervical Foley catheter and intravaginal dinoprostone gel, (2) supracervical Foley catheter and 100 microg oral doses of misoprostol, or (3) serial 100-microg oral doses of misoprostol. Intravenous oxytocin was administered when a protraction disorder of labor was identified.

RESULTS

There were 339 women randomized. There was no significant difference in the time from first intervention to delivery in the 3 groups (P =.546). In each group, a similar percentage of women required oxytocin (P =.103). The rates of cesarean delivery were equivalent among the groups (P =.722). Rates of tachysystole were high but statistically equivalent among the 3 groups. There were no significant differences in Apgar scores or umbilical artery pH.

CONCLUSION

Oral 100 microg serial doses of misoprostol, with or without the use of a supracervical Foley catheter, were equivalent to the use of a supracervical Foley catheter and serial 4-mg doses of dinoprostone gel for cervical ripening and the induction of labor.

Comparison of 25 and 50 microg vaginally administered misoprostol for preinduction of cervical ripening and labor induction

Our purpose was to compare the efficacy of 25 microg and 50 microg intravaginally administered misoprostol tablets for cervical ripening and labor induction. Either 25-microg (n: 58) or 50-microg (n: 56) misoprostol tablets were randomly administered intravaginally to 114 subjects with an unripe cervix for labor induction. The physician was blinded to the medication. Intravaginal misoprostol was given every 4 h until the onset of labor. The mean Bishop score before misoprostol administration was 2.1 +/- 1.6 in the 25-microg group and 2.0 +/- 1.4 in the 50-microg group (p > 0.05). With the 25-microg dose the time until delivery was significantly longer (991.2 +/- 514.4 min vs. 703.12 +/- 432.6 min in the 50-microg group). The use of oxytocin augmentation was significantly higher in the 25-microg group (63.8%) than the 50-microg group (32.1%; p < 0.05). The proportions of patients with tachysystoles and hypersystoles were not significantly different between the two groups (19 and 6.9%, respectively, in the 25-microg group and 25 and 17.8%, respectively, in 50-microg group; p > 0.05). Overall, in the 25-microg group more women achieved vaginal delivery (79.3 vs. 60.7%; p < 0.05). The rate of cesarean sections due to non-reassuring fetal status was higher in the 50-microg misoprostol group (28.6 vs. 10.3%; p < 0.05). The number of neonates with a low 1-min Apgar score (<7) was significantly higher in the 50-microg misoprostol group (26.8 vs. 8.6%; p < 0.05), but 5-min Apgar scores and umbilical artery blood gas values at the time of delivery were not significantly different between the groups (p > 0.05). One patient in the 25-microg group suffered a ruptured uterus. Intravaginal administration of 25 microg of misoprostol is a clinically effective labor induction regimen and has the least adverse effects and complications.