Abstract
Objective In 2012, two Kaiser Permanente Northern California (KPNC) hospitals began offering
outpatient cervical ripening with oral misoprostol under a study protocol. We evaluated
inpatient time from admission to delivery and adverse maternal and neonatal outcomes
associated with outpatient use of misoprostol for cervical ripening among low-risk
women with term pregnancies.
Study Design We conducted a retrospective cohort study comparing three groups: women who received
misoprostol (1) outpatient, under a study protocol; (2) inpatient, at the study sites;
and (3) inpatient, at all KPNC hospitals. Data were obtained from between 2012 and
2017. The primary outcome was time from inpatient admission to delivery. Secondarily,
we evaluated maternal and neonatal outcomes, including the duration and maximum rate
of oxytocin administered, rate of cesarean delivery, incidence of chorioamnionitis
and blood transfusion, Apgar scores, and neonatal intensive care unit admissions.
Demographic and clinical characteristics and outcomes of the outpatient group were
compared with both inpatient misoprostol groups using the appropriate statistical
test. Variables included in the regression analysis were either statistically significant
in the bivariate analyses or have been reported in the literature to be potential
confounders: maternal age at admission, race/ethnicity, body mass index, cervical
dilation at initial misoprostol, and parity.
Results We analyzed data from 10,253 patients: (1) 345 outpatients, under a study protocol;
(2) 1,374 inpatients, at the study sites; and (3) 9,908 inpatients, at all the Kaiser
hospitals. Women in the outpatient group were more likely to be white than both inpatient
groups (63.3 vs. 56.3% at study sites and 47.1% in all hospitals, p = 0.002 and <0.001, respectively); other demographics were clinically comparable. Most
women undergoing labor induction were nulliparous; however, a greater proportion in
the outpatient group were nulliparous compared with inpatient groups (70.8 vs. 61.8%
and 64.3%, p = 0.002 and 0.01). On inpatient admission for delivery, women who received outpatient
misoprostol were more likely to have a cervical dilation of ≥3 cm (39.8 vs. 12.5%
at study sites and 9.7% at all KPNC hospitals, p < 0.001 for both). The outpatient group had a shorter mean time between admission
and delivery (23.6 vs. 29.4 at study sites and 29.8 hours at all KPNC, p < 0.001 for both). The adjusted estimated mean difference between the outpatient
and inpatient group at all the Kaiser hospitals in time from admission to delivery
was −6.48 hours (p < 0.001), and the adjusted estimated mean difference in cervical dilation on admission
was +1.02 cm (p < 0.001). There was no difference in cesarean delivery rates between groups. The
rate of chorioamnionitis in the outpatient group was higher compared with inpatients
at all hospitals (17.7 vs. 10.6%, p < 0.001), but similar when compared with the inpatients at the study sites (17.7 vs. 15.4%,
p = 0.29).
Conclusion Outpatient use of misoprostol for cervical ripening under the study protocol was
associated with reduced inpatient time from admission to delivery compared with inpatient
misoprostol. Although there was a higher rate of chorioamnionitis among outpatients
under the study protocol compared with inpatients at all hospitals, there was no difference
when compared with inpatients at the study sites. There was no difference in rates
of cesarean delivery or maternal or neonatal complications with outpatient misoprostol.
Key Points
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Outpatient misoprostol patients had 6.46 fewer hours from admission to delivery compared
with inpatients at all hospitals.
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There was no difference in the rate of cesareans between the outpatient versus inpatient
misoprostol groups.
-
Other maternal and neonatal complications were low and comparable among outpatients
and inpatients who received misoprostol; this study was not large enough to assess
rare safety outcomes.
Keywords
misoprostol - outpatient - cervical ripening - induction of labor - cesarean delivery
- maternal complications - chorioamnionitis - neonatal complications - inpatient stay
