Alborz University

Background: The success of labor induction is extremely dependent on the state of the cervix. There are various methods available in modern obstetrics practice for ripening the cervix, such as intravaginal prostaglandins and mechanical devices like transcervical catheters. Although plenty of studies have already compared the two methods for the unripened cervices, more studies are warranted in nulliparous patients only. This study aimed to compare the efficacy of intravaginal misoprostol tablets with transcervical Foley catheter for cervical ripening in nulliparous patients.

Methods & Materials: In this randomized clinical trial, 120 nulliparous candidates for labor induction were recruited from two teaching centers in Tabriz within a 17-month period of time. All the enrolled cases had a live singleton fetus with cephalic presentation at term (≥37 weeks), on-admission Bishop Score≤4, intact membranes and reactive non-stress test results. They were randomly assigned to two equal age-matched groups receiving either intravaginal misoprostol (25 microgram, n=59), or transcervical insertion of 16F Foley catheter (n=60).

Results: One time successful induction (i.e. successful induction after a single insertion of misoprostol, or expulsion of transcervical Foley catheter within 12 h of insertion) was achieved in all the patients without employment of other methods such as use of syntocinon. Misoprostol was more effective in terms of induction-to-cervical ripening interval (15.16±3.59 h vs. 18.30±1.59 h; p<0.001). Tachysystole, on the other hand, was significantly more frequent in the misoprostol receivers (25.4% vs. 0%; p<0.001). The two groups were comparable for the rate of cesarean section (misoprostol, 37.3%; Folly catheter, 30%; p=0.40). Comparing the two groups, there was no significant difference with regard to change in Bishop Score (misoprostol, 1.90±0.54 h^-1; Folly catheter, 1.89±0.74 h^-1; p=0.95) and miscellaneous pregnancy-related and fetal complications such as meconium staining of the amniotic fluid, placental abruption/bleeding, uterine atony/hypertonicity, fetal tachycardia/bradycardia, and neonatal apgar.

Conclusion: Intravaginal misoprostol is more efficacious than transcervical insertion of Foley catheter for cervical ripening and induction of labor in nulliparous women.