Multiple protocols and regimens have been studied but, overall, the findings suggest that administering outpatient misoprostol may shorten the time interval to spontaneous labor and decrease the need for a formal labor induction.19-23
Inpatient compared with outpatient prostaglandin use. These trials of “prophylactic” misoprostol generally have compared outpatient administration of misoprostol with placebo. Prostaglandins are one of the most common methods of inpatient cervical ripening, so what about comparisons of inpatient cervical ripening with outpatient prostaglandin administration? There are a handful of studies that make this comparison.
Chang and colleagues looked retrospectively at inpatient and outpatient misoprostol and found that outpatient administration saved 3 to 5 hours on labor and delivery.24 Biem and colleagues randomly assigned women to either inpatient cervical ripening with PGE2 intravaginal inserts or 1 hour of inpatient monitoring after PGE2 administration and then outpatient discharge until the onset of labor or for a nonstress test at 12 hours. They found that those who underwent outpatient ripening spent 8 hours less on labor and delivery and were more highly satisfied with the initial 12 hours of labor induction experience (56% vs 39%; P<.01).25
The largest randomized controlled trial conducted to study outpatient prostaglandin use was the OPRA study (involving 827 women). Investigators compared inpatient to outpatient PGE2 intravaginal gel.26 The primary outcome was total oxytocin administration, which was not different between groups. The study was underpowered, however, as 50% of women labored spontaneously postrandomization. But in the outpatient arm, less than half of the women required additional inpatient ripening, and nearly 40% returned in spontaneous labor, suggesting that outpatient prostaglandin administration may indeed save women a significant amount of time on labor and delivery.
Safety
The safety of outpatient administration of prostaglandins is the biggest concern, especially since, when prostaglandins are compared to outpatient Foley catheter use, Foleys are overall associated with less tachysystole, fetal intolerance, and meconium-stained fluid.3 Foley catheter use for cervical ripening may not be an appropriate choice for all patients, however. For instance, our case patient has a closed cervix, which could make Foley insertion uncomfortable or even impossible. Misoprostol use also offers the potential for flexibility in cervical ripening protocols as patients need not return for Foley balloon removal and indeed labor induction need not take place immediately after administration of misoprostol.
Patients also may prefer outpatient cervical ripening with misoprostol over a Foley. There are some data to suggest that women, overall, have a preference toward prostaglandins; in the PROBAAT-II trial, which compared inpatient oral misoprostol to Foley catheter for cervical ripening, 12% of women in the Foley arm would have preferred another method of induction (vs 6% in the misoprostol arm; P = .02).27 This preference may be magnified in an outpatient setting.
But, again, is outpatient administration of prostaglandins safe? The published trials thus far have not reported an increase in out-of-hospital deliveries or adverse fetal outcomes. However, studies have been of limited size to see more rare outcomes. Unfortunately, an adequately powered study to demonstrate safety is likely never to be accomplished, given that if used responsibly (in low-risk patients with adequate monitoring after administration) the incidence of adverse fetal outcomes during the at-home portion of cervical ripening is likely to be very low. With responsible use, outpatient administration of prostaglandins should be safe. Women are monitored after misoprostol administration and are not sent home if there are any concerns for fetal distress or if frequent contractions continue. Misoprostol reaches maximum blood concentration 30 minutes after oral administration and 70 to 80 minutes after vaginal administration.28 After this time, if contractions start to intensify it is likely that misoprostol has triggered spontaneous labor. In this setting, women are routinely allowed to spontaneously labor at home. One may even argue that outpatient misoprostol could lead to improved safety, as women essentially have a contraction stress test prior to spontaneous labor, and misoprostol administration as an outpatient, as opposed to as an inpatient, may allow for longer time intervals between doses, which could prevent dose stacking.
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