July 29, 2015 —Summary of "Medical Compared With Surgical Abortion for Effective Pregnancy Termination in the First Trimester," Luu Doan Ireland et al., Obstetrics & Gynecology, July 2015.
The majority (65.9%) of abortions in the U.S. take place at nine weeks' gestation or less, according to Luu Doan Ireland, of the University of California-Los Angeles' School of Medicine, and colleagues. They wrote that while surgical abortion still remains the leading procedure for these first-trimester abortions, the use of medical abortion, which currently accounts for 36% of abortions at nine weeks' gestation or less, is increasing.
According to Ireland and colleagues, surgical abortions at nine or fewer weeks' gestation involve "uterine aspiration under local anesthesia with oral premedication or intravenous sedation." Meanwhile, medical abortions at this stage of gestation involve an "evidence-based regimen," in which women take "200 mg mifepristone follow by buccal, sublingual, or vaginal administration of 800 micrograms of misoprostol between 24 and 48 hours later." According to the authors, "Both methods are highly effective with failure rates that are below 5% for either method."
However, the authors noted that little research exists comparing the efficacy of the two procedures, with most research focusing on "outdated medication abortion regimens and surgical techniques." As a result, Ireland and colleagues conducted a "retrospective cohort study ... to compare efficacy, the proportion of pregnancies successfully terminated by the initially chosen method, between medical abortion, using the current evidence-based regimen, and surgical abortion at 9 weeks of gestation or less."
Ireland and colleagues conducted the study at Planned Parenthood Los Angeles, which is "a high-volume health care system providing abortion services at 15 sites throughout the Los Angeles area." The study included 30,146 women who had a surgical or medical abortion at one of PPLA's clinics between Nov. 1, 2010, and Aug. 31, 2013. All of the women were at nine or fewer weeks' gestation.
For the study, the authors reviewed information stored in PPLA patient databases, including:
~ Patient age, race and ethnic background and income levels;
~ Body Mass Index;
~ Confirmation of medical abortion completed;
~ Complications occurring during the eight weeks following the procedures;
~ Gestational age by ultrasonography;
~ Surgical documentation; and
~ Type of abortion procedure performed.
The authors measured the efficacy of medical abortion and surgical abortion based on "successful termination of pregnancy after the initial abortion procedure." Ireland and colleagues also assessed "[s]econdary outcomes," such as any complications.
The study included 13,221 women who underwent medical abortions and 16,925 women who underwent surgical abortions. The two groups had nearly identical mean gestational ages at the time of abortion, at around 6.7 and 6.9 weeks gestation; shared "similar sociodemographic characteristics"; and had similar "[b]ody mass index, gravidity, and parity" characteristics.
The study found that 84% of women who had medical abortions received follow-up care within eight weeks of their initial visits, while 15.9% did not return for follow-up care. The study assumed those women who did not return for follow-up care had uncomplicated, effective medical abortions. Meanwhile, 18% of women who had surgical abortions returned for follow-up care because they experienced persistent problems or had postoperative concerns.
According to the authors, 79 (0.2%) of all the abortion procedures resulted in ongoing pregnancies. Specifically, there were 52 ongoing pregnancies in the medical abortion group, resulting in an efficacy rate of 99.6%, and 27 ongoing pregnancies in the surgical abortion group, resulting in an efficacy rate of 99.8%. Ireland and colleagues noted that while both procedures had high efficacy rates, women opting for medical abortion were four times as likely than those in the surgical abortion group to have an ongoing pregnancy. The study noted that all women in the medical abortion group with ongoing pregnancies opted for aspiration, while 22 of the 27 women in the surgical abortion group had repeat aspiration, three opted for medical abortion and two decided to continue their pregnancies.
Overall, the authors wrote that "abortion type and gestational age had a significant effect on efficacy," adding that "the risk of ongoing pregnancy" in the medical abortion group "increased by 50% for each week of gestational age," while "the risk of ongoing pregnancy decreased by 60% with each week of gestational age among women undergoing surgical abortion."
Meanwhile, Ireland and colleagues found that "[t]here were a total of 382 unanticipated aspirations, accounting for 1.3% of [the] sample." Specifically, the authors noted that 0.6% of women who had surgical abortions had an unanticipated aspiration, with most these women citing "[p]ersistent pain, bleeding, or both" as the most common reasons and a smaller proportion experiencing an ongoing pregnancy. Similarly, 2.2% of women who had medical abortions had an unanticipated aspiration, with most citing similar reasons as women in the surgical abortion group and others having the procedure as a result of an ongoing pregnancy.
According to the authors' analysis, "only abortion type, patient age, and gestational age had a significant effect on a woman's risk of unanticipated aspiration." They noted that "the risk of unanticipated aspiration increased by 3% with each year of patient age" for both procedures, while each "advancing week of gestational age" increased the risk of an unanticipated aspiration for the medical abortion group and decreased the risk for the surgical abortion group.
Meanwhile, the study found that 29 women (0.1%) in the study experienced at least one "major complication" in the eight weeks following either procedure, including "emergency department presentation, hospitalization, uterine perforation, infection, and hemorrhage requiring transfusion." There was "no significant difference between treatment groups," the authors wrote. However, they noted that women in the medical abortion group were at greater risk of experiencing "any adverse event including unanticipated aspiration for persistent symptoms, ongoing pregnancies, and major complications," although the overall rate for such events was only 1.9% across the entire study sample.
Ireland and colleagues noted that when performed at nine or fewer weeks gestation both procedures are "similar in efficacy with success rates greater than 99%." They wrote, "Although there is a statistically significant difference in the risk of unanticipated aspiration between the two methods of pregnancy termination, this risk is overall low in both groups." Further, they noted "[t]here is no difference in the risk of major complications between medical and surgical abortion at this gestational age with a rate of 0.1% for both groups."
The authors concluded, "Provided [women] are appropriate candidates for either method, they should be counseled on both medical and surgical options when seeking pregnancy termination."