OBJECTIVE:

This study was undertaken to determine whether the addition of extra-amniotic saline infusion improves the efficacy of the Foley catheter in nulliparous woman undergoing cervical ripening and induction of labor with an unfavorable cervix.

Study design:

152 nulliparous women with a Bishop score less than ≤4 with singleton gestation, vertex presentation, intact membranes referred for labor induction were randomly assigned to 2 groups: Foley catheter alone or extra-amniotic saline infusion (EASI). All women received concurrent dilute oxytocin infusion.Changes in the Bishop scores, interval to active phase and to vaginal delivery, cesarean rate, and outcomes of labor were assessed. Data were analyzed using analysis or the student t-test.

RESULTS:

146 women were studied after 6 exclusions, 73 were assigned to Foley alone and 73 to EASI. At randomization the groups were similar in potential confounders including: maternal age, gestational age, and indications for induction. The EASI group had a significant improvement in Bishop score, 6 hours after induction. The mean time to active phase was 337±141 minutes and 462±183 minutes for the EASI and Foley group respectively (P<0.0001). The mean time to vaginal delivery was 541±265 minutes and 890±259 minutes for the EASI and Foley group respectively (P<0.0001). The cesarean rate and indications of cesarean were not significantly different between the two groups. There were also no differences in mean neonatal birth weight, low Apgar scores and complications including chorioamnionitis, hyperstimulation and neonatal morbidity.

CONCLUSION:

Our study showed that preinduction cervical ripening by extra-amniotic saline infusion with concurrent oxytocin resulted in greater changes in Bishop score, shorter time to active phase and vaginal delivery than the Foley catheter alone in nulliparous women without increasing the cesarean rate and maternal or neonatal morbidity.

Keywords: Extra-amniotic saline infusion, Foley catheter, Labor induction