Prostaglandin vaginal gel induction of labor comparing amniotomy with repeat prostaglandin gel

Abstract

Objective: The purpose of this study was to compare 2 inductions of labor protocols.

Study design: Women with live singleton pregnancies at ≥37 + 0 weeks gestation who were booked for prostaglandins 2 (PGE2) vaginal gel induction with a modified Bishop's score of <7 were eligible for inclusion. After an evening dose of PGE2 vaginal gel, women were assigned randomly the next morning into the amniotomy or repeat-PGE2 group. The amniotomy group underwent artificial rupture of membranes (ARM), regardless of modified Bishop's score, and received further PGE2 doses only if ARM was not technically possible. The repeat-PGE2 group received further PGE2 (to a maximum of 3 doses) until a modified Bishop's score ≥7 occurred, when an ARM was performed. In both groups, Syntocinon was commenced once membranes were ruptured. The primary outcome measure was time from commencement of induction until birth.

Results: Two hundred forty-five women were assigned randomly into either the amniotomy (n = 121) or repeat-PGE2 group (n = 124). The time for induction of labor-to-birth was >5 hours shorter in the amniotomy group (24.8 vs 30.0 hours; mean difference, 5.2 h; 95% confidence interval, -2.5 to -7.8). Fewer women in the amniotomy group remained undelivered after 24 hours (47.1% vs 67.7%; P < .01). However, the likelihood of an in-hours birth and the length of hospital stay were no different between the groups. There was no difference in the mode of birth or any of the secondary outcomes.

Conclusion: After an initial dose of PGE2 vaginal gel, an amniotomy (once technically possible) is associated with a shorter induction of labor-to-birth time compared with the use of repeat doses of PGE2. Administering more PGE2 with the aim of starting contractions or making the cervix "more favorable," appears to have no clinical advantage.

Keywords: cervical ripening; induced labor.