Myometrial activity after local application of prostaglandin E2 for cervical ripening and term labor induction.

Twelve pregnant women at term with unfavorable cervices (less than or equal to 5 points according to Bishop score) were given prostaglandin E2 for cervical priming and labor induction. Prostaglandin E2 was given in the following manner: 0.5 mg in gel strictly intracervically (n = 4), extraamniotically (n = 4), or prostaglandin E2 (4 mg) in gel vaginally (n = 4). The myometrial activity was registered over a period of 30 minutes before and at least 3 hours after gel application by means of an extraamniotic microtransducer catheter. After both extraamniotic and vaginal gel application, myometrial activity was significantly increased compared with intracervical application. All the women had favorable cervical states 6 hours after treatment and were delivered vaginally within 24 hours. All infants were delivered in good condition with 1-minute Apgar scores greater than 7. From these results we conclude that proper intracervical prostaglandin E2 gel application, in contrast to extraamniotic or vaginal application, induces cervical ripening without significant myometrial activity. Because careful intracervical application appears to avoid or minimize the risks of myometrial hyperstimulation, this technique should be considered particularly in women with unfavorable cervices and delicate fetuses.