The role of ultrasonographic-guided insertion of cervical ripening balloon: A prospective study

Cervical ripening balloon (CRB) is a frequently used technique for non-pharmacologically induction of labor (IOL) in presence of an unfavorable cervix. Successful ripening requires a correct placement of the CRB in the cervical canal. The objective of this study was to evaluate whether ultrasound-guided CRB insertion results more effective in inducing cervical changes than speculum-guided placement.

Prospective observational study including 90 singleton nulliparous pregnancies undergoing mechanical IOL. In 45 women CRB was placed under ultrasonographic control and in 45 under speculum view. The primary outcome was to evaluate any difference in cervical ripening or spontaneous onset of labor at CRB between the 2 groups. Secondary outcomes were: the duration of labor as expressed as the time interval between CRB insertion and delivery and the rate of cesarean section.

The basal characteristics were similar between the 2 groups. After the CRB removal the percentage of women achieving a Bishop score >4 or entering in labor were significantly higher in ultrasonographic assisted group than in the speculum guided group (80 % vs 55.5 % p = 0.023). Bishop score at CRB removal resulted significantly higher in the ultrasonographic assisted group (median 5 vs 2; p = 0.0001) as well its individual changes before and after CRB insertion (median 3 vs 2; p = 0.006). The duration of labor resulted significantly shorter in ultrasound assisted group (median hours 33 vs median 40 p = 0.017), while no differences were found in the incidence of cesarean section (33.3 % vs37.7 %; p = 0.825).

Ultrasound-guided CRB placement induces a better ripening of the cervix resulting in a reduced requirement of using a secondary method of IOL and a shorter duration of labor.