A comparison of 30-, 50-, and 60-mL foley catheter balloon volume and time to achieve cervical ripening for labor induction: A triple-blind randomized controlled trial.

BACKGROUND: Cervical ripening is one of the most important determinants of the outcome of induction of labor. The findings of studies on the most efficacious inflatable catheter balloon volume for pre-induction cervical ripening have been inconclusive.

AIM: To compare the efficacy of the use of different intracervical Foley catheter balloon volumes (30-, 50-, and 60-mL) on cervical ripening.

SUBJECTS AND METHODS: This study was a triple-blind randomized controlled trial. Two hundred and sixteen women with a Bishop score ≤5 at term were randomly assigned into three groups (1:1:1) to receive an intracervical single size eighteen Foley balloon catheter inflated either with 30-mL (control arm) or 50-mL and 60-mL (intervention arm) of sterile saline which was retained for a duration of 12 h. The primary outcome measures were the mean change in Bishop score and achieving a Bishop score of ≥6 at the twelfth-hour post-Foley catheter balloon insertion.

RESULTS: In the total study population and among nulliparous women, the 50-mL and 60-mL balloons compared with the 30-mL Foley catheter balloon achieved a statistically significantly greater mean change in Bishop scores at the twelfth hour\post-insertion (P = 0.005 and P = 0.001), while the 60-mL balloon compared with the 30-mL and 50-mL balloons achieved statistically significant higher mean change in Bishop scores among multiparous women (P = 0.047 and P = 0.003) and cervical dilatation irrespective of parity (P = 0.003 and P = 0.002), at the twelfth-hour post-insertion. The larger catheter balloons were also associated with a statistically significant greater chance of having an induction to delivery interval of <12 h in nulliparous women P = 0.003.

CONCLUSION: The findings of this study showed that the larger single Foley catheter balloon volumes (50-mL and 60-mL) aside from being well tolerated and acceptable have the ability to induce faster changes in Bishop score, produce higher cervical dilation, and thus likely reduce significantly the total labor induction process compared to the 30-mL single catheter balloon volume irrespective of parity.