When a fetal anomaly causes a woman to seek a second-trimester abortion, oral administration of misoprostol appears to be the least effective method for terminating the pregnancy, and vaginal misoprostol administration the most acceptable to women. In a randomized controlled trial, the average time from the start of the procedure to delivery of the placenta was 3-13 hours longer for those given misoprostol orally than for those who received it vaginally or who received intra-amniotic prostaglandin. Women in the vaginal misoprostol group were the most likely to say that if they ever needed a second-trimester abortion again, they would choose the same method.
The trial was conducted between January 1998 and February 2001 at two teaching hospitals in Toronto. Women were eligible if they were 15-24 weeks pregnant and the fetus had a malformation or chromosomal abnormality; those with an allergy to prostaglandins, a history of cesarean delivery or hysterotomy, active bleeding, asthma, a deficiency of amniotic fluid or ruptured membranes were excluded. A total of 217 women were randomized to one of three groups: Eighty-one women received an intra-amniotic injection of prostaglandin, followed by insertion into the cervix of a laminaria tent and intravenous administration of oxytocin; 84 received 400 mcg of vaginal misoprostol every four hours for up to 24 hours; and 52 received the same misoprostol dose, on the same schedule, but orally.
On average, women in all three groups were 32-33 years old and were about 20 weeks pregnant; the majority were white, and almost all were married. Nearly half of participants were nulliparous, and about four in 10 had had an abortion. About three in five had undergone amniocentesis or chorionic villus sampling; chromosomal abnormalities were the most common indication for pregnancy termination.
Complete abortion took an average of 18 hours for women in the vaginal misoprostol group, 21 hours for those who received intra-amniotic prostaglandin and 31 hours for those who took oral misoprostol. The differences between the oral misoprostol group and the others were statistically significant.
No major complications occurred in any group, and rates of many minor complications—nausea, fever, manual removal of the placenta, curettage for undelivered placenta, and vaginal or cervical lacerations—were similar for all three. The frequency of other minor complications, while low, differed by procedure. Women in the intra-amniotic prostaglandin group had significantly more episodes of vomiting requiring treatment than those in the oral misoprostol group (on average, 0.7 vs. 0.2), and the number of episodes of diarrhea requiring treatment was greater among women who took oral misoprostol (0.8) than among those in the other groups (0.1 for each). Additionally, a significantly higher proportion of women in the vaginal misoprostol group, and a marginally higher proportion of those in the oral misoprostol group, than of those in the intra-amniotic prostaglandin group had a live birth (20%, 15% and 5%, respectively). One woman who received vaginal misoprostol and two women in each of the other groups had a failed abortion (i.e., did not go into labor within 48 hours after the start of induction).
During follow-up visits with their physicians three weeks after the abortion, 165 women completed a self-administered questionnaire about the experience. The responses indicated that nausea and vomiting were less of a problem for women given vaginal misoprostol than for others, and that pain from the procedure was least problematic for women who received intra-amniotic prostaglandin and most problematic for those who took oral misoprostol. Notably, 57% of those in the vaginal misoprostol group said that if the need arose again, they would opt for the same procedure to terminate a pregnancy in the second trimester—a significantly larger proportion than gave this answer in the other groups (30-34%). The intensity of pain and the length of time the abortion took were important factors in the decision whether to repeat the procedure.
The researchers note that "investigators have yet to identify the optimal regimens for the use of misoprostol for [second-trimester abortion]." In particular, oral misoprostol procedures require further examination. Meanwhile, they conclude, before choosing a method for second-trimester abortion, women who are carrying a fetus with a malformation or a chromosomal abnormality should be given information about the relative effectiveness and acceptability of available regimens.
1 . Akoury HA et al., Randomized controlled trial of misoprostol for second-trimester pregnancy termination associated with fetal malformation, American Journal of Obstetrics and Gynecology, 2004, 190(3):755-762.