A prospective double blind trial investigating impact of vaginal pH on efficacy of prostaglandin gel for cervical ripening and course of labour

Effect of acidic vaginal pH on the efficacy of dinoprostone (PGE2) vaginal tablet for labor induction in full term pregnant women: a randomized controlled trial

OBJECTIVES

There is controversial evidence that acidification of vaginal pH may increase the efficacy of vaginal prostaglandins in labor induction, with research being mainly focused on misoprostol. This study aims to evaluate the impact of this intervention on the progress of labor induction with dinoprostone (PGE2) vaginal tablet.

METHODS

This double-blind, parallel-group, randomized study was conducted between October 2021 and December 2022 at Alexandra General Hospital, Athens, Greece. A total of 230 women with singleton, full term pregnancy that were scheduled for labor induction were randomly divided into two groups: Group A, who received acidic vaginal wash (5 % acetic acid) and Group B, who received a normal saline vaginal wash. Afterwards, participants received a vaginal tablet of 3 mg dinoprostone every 6 h (maximum two doses).

RESULTS

There were no statistically significant differences in mode of delivery, duration of different labor stages, Bishop score changes and possible complications. Participants in the acidification group needed less often labor augmentation with oxytocin and epidural anesthesia (p=0.03).

CONCLUSIONS

Vaginal acidification seems to have no effect on the efficacy of the dinoprostone vaginal tablet. Even though it may reduce the need for oxytocin augmentation, there is no apparent benefit on clinical outcomes, such as reduction in cesarean section rates or shorter labor duration. Future research is necessary in order to validate these findings.

The impact of vaginal pH on induction of labour outcomes: a meta-analysis of observational studies

The present meta-analysis evaluates the impact of an acidic vaginal pH on the progress of labour induction with dinoprostone and misoprostol. We searched Medline, Scopus, EMBASE, Cochrane Central Register of Controlled Trials CENTRAL, Clinicaltrials.gov and Google Scholar databases for relevant studies. Meta-analysis was performed with Rstudio using the meta function and trial sequential analysis was used to evaluate the adequacy of sample size. Nine studies were retrieved that involved 809 patients. An acidic vaginal pH did not influence the efficacy of misoprostol or dinoprostone in terms of accomplishing a successful vaginal delivery (OR 0.62, 95% CI 0.29, 1.30). The interval to delivery was unaffected by the acidity of vaginal pH (Mean Difference 4.18 h, 95% CI -2.09, 10.45). In conclusion, vaginal pH does not seem to affect the potency of vaginally administered prostaglandins; therefore, moistening of vaginal tables with acetic acid does not seem reasonable until further evidence becomes available.

Effect of vaginal pH on efficacy of dinoprostone gel for labour induction: a cross-sectional study

The purpose of this study was to assess the effect of vaginal pH on efficacy of intracervical dinoprostone gel (PGE2) for labour induction, progression and induction delivery interval. A cross-sectional study was done among 150 term pregnant women planned for induction with unfavourable Bishop's score ≤5. Women were categorised into two groups based on vaginal pH >4.5 and ≤4.5. Induction was done with maximum of three doses of PGE2 based on Bishop's score, followed by oxytocin administration. Failed induction rate was 14.5%. There was no significant association between vaginal pH and Bishop's score change after first gel application. There was no significant difference in failed induction rates, time from induction to active labour as well as induction delivery interval between two groups. Similarly, there was no significant association between oxytocin requirement and mode of delivery with vaginal pH. Intracervical PGE2 is an ideal route, unaffected by vaginal pH.Impact StatementWhat is already known on this subject? Prostaglandins are organic acids that have diminished solubility in aqueous solution with a low pH. The release of the drug could be altered by the acidity of vagina and this could result in variable clinical response. Vaginal pH may alter the efficacy of intravaginally administered prostaglandins through several potential mechanisms.What the results of this study add? There was no significant effect of change in vaginal pH on effectiveness of intracervical administered PGE2. There was no significant association between vaginal pH and time from induction to time women is entering into active labour as well as time from induction to delivery. Similarly, there was no significant association between mode of delivery and oxytocin usage with vaginal pH in labour. Intracervical PGE2 is an ideal route, unaffected by vaginal pH.What the implications are of these findings for clinical practice and/or further research? Further randomised studies are required comparing both vaginally administered PG inserts and intracervical PGE2 gels with vaginal and cervical pH, to directly compare their effectiveness in labour induction.

Effect of vaginal washing before intravaginal dinoprostone insertion for labor induction: A randomized clinical trial

AIM

Prostaglandins have a dual action of cervical ripening and induction of uterine contraction. This study was designed to compare the effectiveness of vaginal washing just before insertion of intravaginal dinoprostone.

METHODS

A randomized controlled trial was conducted at the Zeynep Kamil Women and Children's Health Training and Research Hospital. One hundred and ninety-one women with singleton, term pregnancy who underwent labor induction were randomly assigned to two groups: Group 1 consisted of 95 pregnant women with vaginal washing before intravaginal dinoprostone (Propess system for slow release system of 10 mg of dinoprostone) insertion (study group), and 96 pregnant women constituted the control group who did not undergo vaginal washing before intravaginal dinoprostone insertion. A parallel randomized controlled trial was conducted with an allocation ratio of 1:1 to compare the effectiveness of vaginal washing before intravaginal dinoprostone insertion.

RESULTS

The groups had similar mean age, body mass index, gestational age, gravidity, parity and Bishop score before agent insertion (P > 0.05). Duration of dinoprostone kept intravaginally, duration from the beginning of dinoprostone insert vaginally to the active phase of labor and duration from the time of intravaginal dinoprostone insertion to delivery were significantly longer in the control group (P < 0.05). Uterine hyperstimulation rate was significantly higher in study group compared to control group (P < 0.05). Meconium passage, fetal infection and neonatal intensive care unit admission were significantly higher in the control group (P < 0.05).

CONCLUSION

Vaginal washing before intravaginal dinoprostone insertion may increase Prostaglandin E2 bioavailability as we found shorter duration and better outcome of labor induction in the present study.

Vaginal acidity enhancement with a 3% acetic acid gel prior to misoprostol treatment for pregnancy termination in the midtrimester

OBJECTIVE

To investigate whether enhancing vaginal acidity improves the success of medical abortions in the midtrimester.

METHODS

A double-blind, randomized, placebo-controlled trial was conducted with 48 women with missed midtrimester abortions. Twice daily, the study participants (n=24) were treated with a 3% acetic acid gel and the controls (n=24) with a placebo gel, starting 2 days prior to initiating the misoprostol treatment. The primary outcome measures were the rates of successful abortion within 24 and 48 hours. Secondary measures included gel tolerability and adverse effects of the misoprostol treatment.

RESULTS

The success rates were higher in the study group, within both 24 hours (11/23 vs 3/24; P=0.011) and 48 hours (18/23 vs 6/24; P<0.001). Among the women with a vaginal pH of 5 or higher at baseline, acidic gel was also associated with higher success rates within 24 hours (8/13 vs 2/15; P<0.01) and 48 hours (13/13 vs 3/15; P<0,001). The vaginal gels were well tolerated and the misoprostol treatment produced no serious adverse effects.

CONCLUSION

A 3% acetic acid gel appears to be an effective and safe preparatory adjuvant to vaginal misoprostol treatment for midtrimester medical abortions, especially in women with a vaginal pH of 5 or higher. www.controlledtrials.com: ISRCTN75746444.