Office-based ambulatory cervical ripening prior to inpatient induction of labor

Dilapan-S and laminaria

There are many published studies using Dilapan-S and laminaria for cervical preparation prior to uterine evacuation.¹² There are few published studies using Dilapan-S or laminaria for CR prior to IOL. In a pilot study, 21 patients were randomly assigned to outpatient versus inpatient Dilapan-S for CR the night prior to scheduled oxytocin IOL.¹³ The length of time from initiation of oxytocin to delivery in the outpatient and inpatient groups was similar (11 vs 14 hours, respectively). The outpatient compared with the inpatient group had a shorter length of hospitalization until delivery (51 vs 70 hours).

In other studies of Dilapan-S for CR, the patients remained in the hospital once the dilators were inserted. In one small trial, 41 women were randomized to CR with Dilapan-S or laminaria. As many dilators as could be comfortably tolerated by the patient were inserted.¹⁴ The mean numbers of Dilapan-S and laminaria dilators inserted were 4.3 and 9.7, respectively. The morning after the insertion of the dilators, oxytocin IOL was initiated. The times from initiation of oxytocin to delivery for the women in the Dilapan-S and laminaria groups were 11.6 and 15.5 hours, respectively.

An observational study reported on outcomes with Dilapan-S for CR on inpatients.¹⁵ In the study 444 women scheduled for IOL at 37 to 40 weeks’ gestation, with a mean baseline Bishop score of 2.9, had Dilapan-S placed for approximately 15 hours prior to oxytocin IOL. The mean number of Dilapan-S dilators that were inserted was 3.8. The study protocol prohibited placing more than 5 cervical dilator devices. The mean Bishop score after removal of the dilators was 6.5. The most common adverse effects of Dilapan-S CR were bleeding (2.7%) and pain (0.2%). The cesarean delivery rate in the cohort was 30.1%. An Apgar score <7 at 5 minutes was recorded for 3 newborns. An umbilical artery pH of <7.10 was observed in 8 newborns.

In a randomized trial performed on inpatients, 419 women undergoing CR were assigned to a Foley balloon or Dilapan-S.¹⁶ The vaginal delivery rates were similar in the groups—76% for Foley and 81% for Dilapan-S. Maternal and neonatal adverse effects were similar between the two groups. Compared with Foley catheter, women assigned to Dilapan-S reported greater satisfaction with their CR experience, more sleep, and more ability to perform daily activities.

Misoprostol and dinoprostone

Both misoprostol and dinoprostone are effective for outpatient CR. However, a Cochrane systematic review and meta-analysis concluded that balloon CR, compared with prostaglandin CR, is probably associated with a lower risk of uterine hyperstimulation with concerning fetal heart rate changes.¹⁷ Because misoprostol and dinoprostone occasionally can cause uterine hyperstimulation with fetal heart changes, many experts recommend CTG monitoring both before and after administration of misoprostol or dinoprostone for CR.

In a trial of outpatient versus inpatient vaginal PGE₂ CR, 425 women at 37 to 42 weeks’ gestation were assigned randomly to outpatient or inpatient CR.¹⁸ All women had CTG monitoring for 20 minutes before and after vaginal placement of the PGE₂ gel. The PGE₂ dose was 2 mg for nulliparous and 1 mg for parous women. The cesarean delivery rates were similar in the outpatient and inpatient groups—22.3% and 22.9%, respectively. Among the women randomized to outpatient CR, 27 women (13%) could not be discharged home after administration of the vaginal PGE₂ because of frequent uterine contractions or an abnormal fetal heart rate pattern. In addition, 64 women (30%) in the outpatient group returned to the hospital before scheduled induction because of frequent contractions. Maternal and neonatal complications were similar in the two groups. The investigators concluded that, at the dose and route of prostaglandin utilized in this study, the resultant rates of abnormal fetal heart rate pattern and frequent contractions might reduce the clinical utility of outpatient vaginal prostaglandin CR.

Another study also reported a greater rate of uterine tachysystole with vaginal PGE₂ compared with a Foley catheter for CR (9% vs 0%).¹⁹ In a Cochrane systematic review of vaginal prostaglandin for CR, compared with placebo, vaginal prostaglandins were associated with a significantly greater rate of uterine hyperstimulation with fetal heart rate changes (4.8% vs 1.0%).²⁰ Other studies also reported the feasibility of outpatient CR with vaginal prostaglandin.^21,22

Both oral and vaginal misoprostol have been utilized for outpatient CR. In one study, 87 women with singleton pregnancy at 40 to 42 weeks’ gestation with a Bishop score <6 were randomized to outpatient CR with oral misoprostol (100 µg) or placebo.²³ Following administration of the oral misoprostol, the women had 2 hours of CTG monitoring. The treatment was repeated daily for up to 3 days if there was no change in the cervix. If labor occurred, the patient was admitted to the labor unit for oxytocin IOL. The times from first dose of misoprostol or placebo to delivery were 46 and 84 hours (P<.001), respectively.

In another study, 49 women ≥40 weeks’ gestation with a Bishop score <5 were randomly assigned to receive outpatient oral misoprostol 25 µg or 50 µg.²⁴ The dose could be repeated every 3 days over 9 days if ripening or labor had not been achieved. The women had CTG before administration of oral misoprostol. After the misoprostol dose, they had 2 hours of CTG monitoring. The number of doses received by the women assigned to the 50 µg group were 83%, 13%, and 4% for 1, 2, and 3 doses, respectively. The number of doses received by the women assigned to the 25 µg group were 58%, 26%, and 16% for 1, 2, and 3 doses, respectively. The mean intervals from initiation of CR to delivery in the 25 µg and the 50 µg groups were 3.9 and 2.5 days, respectively. The investigators reported no maternal or newborn adverse events, although the study was not powered to detect infrequent events.

Many studies have reported on the feasibility of outpatient CR with vaginal misoprostol.^25-30 In one study, 77 women at 40 weeks’ gestation and a Bishop score ≤8 were randomized to a single dose of vaginal misoprostol 25 µg or gentle cervical examination (control).²⁵ The women had 1 hour of CTG monitoring after the intervention. If they had regular contractions they were admitted to the birthing unit. If they had no regular contractions they were discharged home. For nulliparous women, the time from intervention to delivery in the misoprostol group was 4.9 days, and 8.1 days in the control group. For parous women, the times from intervention to delivery in the two groups were 3.8 and 6.9 days, respectively.

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