Success was defined in these trials as complete abortion without the need for surgery. This definition provides a clear end point for research purposes. It is also a logical way to operationalize success in light of patients' goals, as many women opt for medical abortion because they want to avoid surgery and anesthesia.
 

After reading this section, you should be able to answer the following question: Using the FDA-approved protocol, what percentage of medical abortions are "unsuccessful" and require intervention to treat ongoing pregnancy, incomplete abortion, or other medical conditions?

Efficacy
In 1993, Peyron and colleagues⁷ published the findings from two consecutive trials of the standard mifepristone/misoprostol regimen. In both studies, women received mifepristone 600 mg followed in 48 hours by 400 µg of misoprostol orally. Women enrolled in the second study were offered another misoprostol 200-µg dose if they had not aborted within 4 hours of taking the first dose of misoprostol. All women in the first study and 91% of women in the second study had pregnancies ≤ 49 days' gestation. The remaining 9% in the second study were 50 to 59 days' gestation.

In Study 1, the success rate was 96.9%. The failures included ongoing pregnancies (0.8%), incomplete abortions (1.8%), and vacuum aspiration for prolonged uterine bleeding (0.4%). In Study 2, the overall rate of success of the regimen with the optional second dose of misoprostol was 98.7%. The rates of ongoing pregnancy and incomplete abortion were 0.6% and 0.5%, respectively.

Ostensibly one might interpret the approximate 2% difference in success rates between trials as evidence that two sequential doses of misoprostol is a more effective approach. However, there was a large difference in abortion rates within 4 hours of taking one dose of misoprostol (60.9% in the single-dose study and 69.1% in Study 2). Therefore, these findings don't clearly support the hypothesis that the second dose of misoprostol increases efficacy.

In 1995, Aubény and colleagues⁸ reported similar findings from a different multicenter French trial that offered medical abortion to women with pregnancies of ≤ 63 days' gestation. As in the previous trial, subjects received the standard mifepristone/misoprostol regimen; however, these women were offered an additional dose of misoprostol earlier than in Peyron's second study (after 3 hours) if they had not aborted.

The success rate for gestations of 49 days or less was 95.5%, with rates of 1.2% and 3.1% for ongoing pregnancy and incomplete abortion, respectively. Complete abortion rates decreased slightly to 93.4% at 50 to 56 days' gestation and then declined to 86.8% at 57 to 63 days. The additional dose of misoprostol did not significantly improve overall efficacy when compared to an earlier study by the same researchers using a single dose of misoprostol.

The U.S. trial was the largest of the three clinical trials that employed the standard mifepristone/misoprostol regimen. This multicenter study by Spitz and colleagues⁹ included 2,121 women with pregnancies of ≤ 63 days' gestation. Participants were divided into three groups based on gestational age (≤ 49 days, 50 to 56 days, and 57 to 63 days). The success rate in women with gestations of 49 days or less was lower (92%) in this trial than in the French studies; the rate of ongoing pregnancy (1%) was nearly the same, but the incomplete abortion rate (5%) was somewhat higher.

The authors speculated that the relative lack of experience of U.S. practitioners with medical abortion may have led them to diagnose and treat incomplete abortion more often than their French counterparts. However, no formal analysis or published evidence exists to prove this supposition. Click here to view Figure 5.

In these three published reports involving the standard regimen, more than half of women aborted within 4 to 5 hours after misoprostol administration. Approximately 80% aborted within 24 hours of taking misoprostol.^7-9 Click here to view Figure 6.

Another trend noted in these studies was the relationship between the efficacy of the procedure and gestational age. In general, efficacy rates are lower after 49 days' gestation. Data from the trial by Spitz and colleagues⁹ are representative. Click here to view Figure 7. The standard regimen, however, remains quite effective up to 56 days' gestation. Ngoc and colleagues¹¹ reported success rates of 96% in Vietnamese women ≤ 56 days' gestation, and Winikoff and colleagues¹² reported success rates between 84% and 95% for the same gestational age range in China, Cuba, and India.

Back to top

Click here to check your understanding.
 

After reading this section, you should be able to answer the following questions: Aside from vaginal bleeding and pain, which side effects of the standard regimen are the most common? By which day do most women using the standard regimen report their bleeding as "spotting"?

Side Effects
Vaginal bleeding is expected during the abortion process and was routinely reported by women in whom medical abortion succeeded. Women in the U.S. trial who were 49 days' gestation or less reported bleeding for a median of 13 days. Bleeding was heaviest on the day of misoprostol administration.

By day 15, the majority (77%) of women described their bleeding as "spotting." After 30 days, 9% of the women reported some type of bleeding; this percentage dropped to 1% after 60 days. Excessive bleeding required blood transfusions in four women (0.2%) and accounted for 25 of 27 emergency department visits or hospitalizations and 56 of 59 surgical aspirations. Interventions for bleeding were twice as common in women whose pregnancies were > 49 days' gestation (p = .008).⁹

In general, side effects reported in trials of the standard regimen tended to occur more often in women with more advanced pregnancies. The medical literature contains no reports of laparotomy or hysterectomy for hemostasis after medical abortion.

Nearly all (97%) of the women in the U.S. trial reported abdominal pain. Sixty-eight percent of women received at least one pain medication (usually acetaminophen), while 29% also were treated with opiates. Women whose gestations were ≥ 50 days received significantly more analgesics than those ≤ 49 days (p < .001). Aside from bleeding and pain, the most common side effects reported in the three large trials with the standard regimen were gastrointestinal in nature - nausea, vomiting, and diarrhea.^7-9 Click here to view Figure 8.

Back to top

Click here to check your understanding.
 

Proceed to Evidence-Based Variations of the Standard Regimen.

References for this module

©2009 Copyright National Abortion Federation
Disclaimer | Contact Us