Background
By being noninvasive, medical termination of pregnancy has increased worldwide access
to abortion and improved safety of unsafe abortion. However, secondary surgical intervention
is the most frequent complication to medical abortion.
Objective
We aimed to identify and quantify risk factors for surgical intervention in women
undergoing medically induced termination of pregnancy before 9 completed weeks of
gestation.
Study Design
We conducted a nationwide cohort study, including all pregnancies terminated before
63 gestational days in women aged 15–49 years during the period 2005–2015. Induction
regimen was 200 mg mifepristone followed 24–48 hours later by 0.8 mg vaginal misoprostol.
All included pregnancies were followed up for 8 weeks from mifepristone administration.
Data were retrieved from national health registers. Multiple logistic regression provided
adjusted odds ratios of surgical intervention with 95% confidence intervals. The discriminative
ability of the risk factors in identifying surgical intervention was assessed by cross-validated
area under the receiver operating characteristic curve.
Results
Of 86,437 early medical abortions, 5320 (6.2%) underwent a surgical intervention within
8 weeks after induction. The proportion of surgical interventions increased from 3.5%
in the 5th to 6th gestational week to 10.3% in week 9, odds ratio, 3.2 (95% confidence
interval, 2.9–3.6). Compared with women aged 15–19 years, the risk of surgical intervention
increased with increasing maternal age until the age of 30–34 years, odds ratio, 1.7
(95% confidence interval, 1.5–1.9), where after the risk decreased to an odds ratio
for age group 40–49 of 1.2 (95% confidence interval, 1.0–1.4). Compared with nulliparous
women, a history of only vaginal deliveries with spontaneous delivery of placenta
implied an odds ratio of 1.1 (95% confidence interval, 1.0–1.2), women with a history
of at least 1 cesarean delivery, an odds ratio of 1.5 (95% confidence interval, 1.3–1.6),
and women having experienced a manual removal of placenta after a vaginal birth, an
odds ratio of 2.0 (95% confidence interval, 1.7–2.4). Previous medically induced abortion
decreased the risk of surgical intervention, odds ratio 0.84 (95% confidence interval,
0.78–0.91), whereas previous early (before 56 days of gestation) surgically induced
abortion implied a 53% (95% confidence interval, 1.4–1.7) increased risk of surgical
intervention. Previous surgical abortion after 55 days of gestation increased the
risk by 17% (95% confidence interval, 1.1–1.3). The area under the receiver operating
characteristic curve of the model including all quantified risk factors was 63% (95%
confidence interval, 62-64%).
Conclusion
Gestational age, maternal age, previous deliveries, and history of medically and surgically
induced abortions all had a significant influence on the risk of surgical intervention
of early medical abortion. However, inclusion of all quantified risk factors still
left most interventions unpredictable.
Key words
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Article info
Publication history
Published online: February 11, 2019
Accepted:
February 9,
2019
Received in revised form:
January 16,
2019
Received:
October 29,
2018
Footnotes
The authors report no conflict of interest.
The study was supported by Department of Gynecology, Copenhagen University Hospital, Rigshospitalet, Denmark.
Cite this article as: Meaidi A, Friedrich S, Gerds TA, et al. Risk factors for surgical intervention of early medical abortion. Am J Obstet Gynecol 2019;220:478.e1-15.
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