Misoprostol priming prior to second trimester medical abortion.

⁎ Corresponding author. 85 East Concord St, 6th Floor, Boston, MA 02130, USA. Tel.: +1 617 414 5593; fax: +1 617 414 7300. E-mail address: Nilda.Moreno@BMC.org (N.L. Moreno-Ruiz). Priming refers to the use of medication or procedures to ready the cervix and uterus, producing more effective uterine contractions and shortening the course of labor. Priming is used extensively before induction of labor for term pregnancy [1–3]. Effective pharmacologic agents used for cervical priming at term include 10-mg dinoprostone vaginal inserts, 0.5-mg dinoprostone vaginal gel [1,2], misoprostol 25–50 μg vaginally [3–5], and mifepristone 200 mg orally [6]. In the United States, neither misoprostol nor mifepristone is approved for priming. Medical or labor induction abortion in the second trimester has the disadvantage of variable and frequently prolonged inductions, requiring overnight hospitalization. In our institution, induction abortion using misoprostol alone has a median time of 14 hours. An effective method of priming would decrease induction time and increase the likelihood of same day discharge. Mifepristone has been shown to decrease induction time—the interval between the start of misoprostol administration and fetal expulsion—by 40% to 45% [7]. However, mifepristone is not available to all institutions, while misoprostol generally is available. There is extensive experience with misoprostol for priming at term and as an uterotonic agent [8]. Before mifepristone was available for induction in our institution, we investigated the use of 50 μg of misoprostol administered buccally the evening before induction. The objective of the present study was to evaluate this method of priming on the length of induction abortion. The study was approved by the Boston University Institutional Review Board. Women were considered eligible if they were 18 years or older, had an ongoing normal pregnancy between 18 and 24 weeks, and had completed evaluation and consent for induction abortion with misoprostol. As part of routine abortion care, women received an intra-amniotic injection of 1.5 mg of digoxin for feticide. After feticide, women who agreed to participate were enrolled. A single dose of 50 μg of misoprostol (half of a 100-μg tablet) was dispensed with instructions to use the tablet buccally for 30 minutes between 8:00 to 10:00 PM the evening prior to induction. Women returned to the hospital the following morning to start inductionwith misoprostol, 400 μg buccally every 4 hours, until expulsion occurred. Symptoms and adverse effects were recorded. Demographic and induction data were also collected. The primary outcome was abortion time (the interval between the first full dose of misoprostol and fetal expulsion), which in our institution was 14 hours (95% CI, 11–16.5) without priming. A sample size of 19 womenwas calculated to determine a 2-sided CI for a single mean with no more than 1.5 hours of deviation. Nineteen women with gestational ages between 18 and 23 weeks were enrolled from January to October 2007. Fifteen women were multiparous and 4 were nulliparous. The mean gestational age was 20.9±1.3 weeks. The median interval between the evening dose prior to induction of 50 μg misoprostol and the start of induction was 11.6 hours (range, 10.50–14.0 hours). Overnight, 3 women had nausea or vomiting. Elevenwomen had cramping, starting amean of 1.6 hours after the priming dose (range, 0.25–6.0 hours). No woman started labor before admission. The median time from first dose of misoprostol on the morning of induction to expulsion for all womenwas 9.4 hours (95% CI, 8–19); the shortest interval was 2.3 hours. The median induction time was 7.4 hours (95% CI, 6–11) for multiparous women (n=15). Nulliparous women had induction times that ranged from 7.8 to 24 hours. Two women had instrumental removal of the placenta. There were no complications. Eight women were discharged the same day of admission; the remaining 12 women went home the next day. The present study suggests that the use of misoprostol the day prior to induction has merit as a priming agent. The length of induction can be contrasted with a historical cohort in our institution; the median abortion time for induction decreased 33% with priming. The decrease in induction time is most striking for multiparous women. As there were only 4 nulliparous women, comparison is very limited but the decrease is not evident. There are a few other studies that used misoprostol as a priming agent. In one, 2 doses of 400 μg of oral misoprostol were used every 12 hours prior to induction with 400 μg of misoprostol every 6 hours. The women with priming had median induction times of 9 hours compared with 13 hours for the group without priming [9]. In contrast, a randomized trial of 400 μg of oral misoprostol 12 hours prior to gemeprost induction did not show a beneficial effect [10]. An effective priming agent could decrease induction time and hospital utilization and costs. Our experience suggests that misoprostol has potential as a priming agent for women who undergo induction termination of pregnancy. In our small sample, it appeared that the effect was more marked in multiparous women. Further evaluation, including comparison with mifepristone, would be useful.