To assess the risk of uterine rupture when using current mifepristone and misoprostol
regimens for second-trimester abortion among those who had a prior cesarean section
After prospectively registering on PROSPERO (CRD42022302626), we systematically searched
PubMed, EMBASE, POPLINE, ClinicalTrials.gov, and Cochrane Library using search terms
“second-trimester,” “induction,” “mifepristone,” and “abortion” from inception until
January 2022. We limited our sample to studies including pregnancies of 14–28 weeks’
gestation, studies with a mixed cohort with and without uterine scar, and studies
available in English. We excluded case reports and narrative reviews. Two authors
independently reviewed studies. Absolute risk with binomial confidence intervals was
calculated from pooled data. Using R software, total risk difference was estimated
by the Mantel-Haenszel random effects method without continuity correction. For studies
with zero events, a continuity correction of 0.5 was applied in the forest plot for
individual risk differences. Statistical heterogeneity was assessed with Higgins I2
statistics. Funnel plot assessed for publication bias.
Of 198 articles identified, 19 met inclusion criteria: seven randomized trials (n=923)
and 12 observational studies (n=2,589). Uterine rupture risk with prior cesarean birth
was 1.8% (7/385) (95% CI, 0.7–3.7) and without was 0.1% (2/3,127) (95% CI, 0.0–0.2).
The risk difference was 0.01 (95% CI, 0.00–0.03; I2=0%). Minor funnel plot asymmetry
demonstrated low evidence of publication bias.
Uterine rupture during second-trimester abortion is a rare event but risk does appear
to increase among those with a prior cesarean section birth. In the context of patient-centered
counseling, this may be acceptable to both patients and providers.