The Effect of Vaginal pH on the Efficacy of Vaginal Misoprostol for the Induction of Midtrimester Pregnancy Termination

Abstract

Background: Vaginal misoprostol is said to dissolve better in an acidic environment, thus, in this study we aimed to evaluate the influence of increasing vaginal acidity on the effectiveness of vaginal misoprostol for the induction of midtrimester pregnancy using acidic environment.

Effect of vaginal washing before Misoprostol insertion on cervical ripening before induction of labor: A randomized single‐blind clinical trial

“…On the other hand, conflicting results have been obtained in studies that the researcher's hypothesis was prostaglandins are effective in acidic media. Some studies have reported that acidic vaginal pH in the first and second trimesters has no effect on the induction of labor with Misoprostol, 14,19 while Rashwan et al reported positive and effective results 12 . According to the results of indirect studies, it is not yet possible to make an accurate conclusion about the effect of pH on the induction of the labor process.…”

“…[10][11][12][13]18 Other studies suggest that when the acidic environment in the vagina is created with acetic acid, the success rate of Misoprostol increases 12,13 and some studies have considered the effectiveness of vaginal Misoprostol in moderate acidity 5 and refused the effect of acidic environment. 14 of prostaglandins, reducing the active phase of labor. 15,16 Finally, Chandra et al have reported no efficacy and the optimal pH for achieving maximal Misoprostol efficacy has not yet been identified.…”

“…Success rates between 24 and 48 hours, adverse effects and mean termination time, total Misoprostol consumption, and the number of curettages was comparable between groups, but it was observed that increased vaginal acidity did not improve the effectiveness of vaginal Misoprostol for termination of second-trimester pregnancy. 14 Another study was conducted by Najafian to evaluate the effectiveness of vaginal Misoprostol and vaginal washing with 3% acetic acid for termination of pregnancy in the first trimester. Their results showed that vaginal washing with acetic acid had no effect on induction of first-trimester abortion compared to the control group.…”

“…Overall, 95% of pregnancies were successful in the acetic acid group compared to 85% in the control group, but this difference was not statistically significant. Success rates between 24 and 48 hours, adverse effects and mean termination time, total Misoprostol consumption, and the number of curettages was comparable between groups, but it was observed that increased vaginal acidity did not improve the effectiveness of vaginal Misoprostol for termination of second‐trimester pregnancy 14 . Another study was conducted by Najafian to evaluate the effectiveness of vaginal Misoprostol and vaginal washing with 3% acetic acid for termination of pregnancy in the first trimester.…”

“…12,13 Other studies have found more efficacy for vaginal Misoprostol in moderate acidity and refused the effect of an acidic environment. 14 In an in vitro study comparing Dinoprostone releasing at vaginal pHs of 7.4, 5.4, and 3.4, it was found that prostaglandin releasing was reduced in acidic pH, and an optimal pH for this purpose is 7.4. 7 The vaginal pH in pregnancy is acidic and vaginal washing reduces the normal flora of the vagina and changes the pH to alkaline, and it seems that according to this hypothesis, Misoprostol can be more effective in a thinner environment and higher pH.…”