Recommendation:
- Less than 22-24 weeks gestation with one uterine scar:Â No changes to recommended regimens necessary.
- More than 22-24 weeks gestation with one uterine scar or 13-24 weeks gestation with more than one uterine scar: Consider decreasing the misoprostol dose with or without lengthening the misoprostol dosing interval. There is insufficient evidence to know if this impacts the risk of uterine rupture.
Strength of recommendation: Weak
Quality of evidence: Very low
Risk of uterine rupture with medical abortion
Uterine rupture has been reported during medical abortion at or after 13 weeks gestation in people with and without a uterine scar. A meta-analysis of 22 studies including 7,118 participants undergoing medical abortion with mifepristone and misoprostol found a uterine rupture risk of 1.1% in women with a prior scar, compared to 0.01% in those without a scar (Henkel et al., 2023). In a meta-analysis of 16 studies of 3,556 women undergoing medical abortion at or after 13 weeks gestation with combined or misoprostol-only regimens, three women suffered uterine rupture resulting in a rate of 0.28% with a previous cesarean section and 0.04% without (Goyal, 2009). Risk of rupture appears to increase when more than one scar is present (Latta et al., 2023; Zwerling et al., 2024)
Additional misoprostol-only studies published since the meta-analysis referenced above have found that uterine rupture is rare, even with multiple scars. A single-center prospective comparative cohort included 158 people without a prior scar, and 80 people with a scar undergoing misoprostol-only medical abortion between 14 and 28 weeks, finding no differences in abortion success or induction-to-abortion interval. One person in the scar group experienced a uterine rupture (1.3%) (Pongsatha, Suntornlimsiri, & Tongsong, 2024). A single-center retrospective review of 279 women undergoing abortion between 14-26 weeks included 60 women with one and 26 women with more than one uterine scar (Küçükgöz Güleç et al., 2013). Women received misoprostol 200mcg vaginally every four hours; three had a uterine rupture. In another retrospective review of 263 women between 12-24 weeks undergoing misoprostol-only abortion, 48 had one and 29 had more than one scar; one rupture was observed in a woman with three prior cesarean sections who received a misoprostol regimen of 200mcg sublingually every three hours (Cetin et al., 2016). A third retrospective review included 231 women with one and 37 women with two prior cesarean deliveries, and used a regimen of 800mcg of misoprostol as a loading dose followed by 200mcg every two hours for three doses; no one experienced rupture (Torriente, Steinberg, & Joubert, 2017). A retrospective cohort that compared women with no scar (n=80) to those with 1 scar (n=79) and with 2 scars (n=58) found no difference in complications between the groups when either misoprostol 400mcg, or misoprostol 400mcg followed by repeated doses of 200mcg was used (Erturk et al., 2022). One patient with 2 scars experienced uterine rupture; they received the lower dose misoprostol regimen. One single-center prospective study of 250 women undergoing uterine evacuation for fetal demise using a low-dose misoprostol regimen included 95 participants with a uterine scar (Shakir, 2022). Those with gestations between 13-17 weeks received 100mcg of misoprostol vaginally every six hours for 24 hours, and between 18-24 weeks received 50mcg of misoprostol. No ruptures occurred, however only 67% had completely aborted after 24 hours.
Regimen for people with a uterine scar
Due to the rarity of uterine rupture in individuals with a previous scar, no clear guidance can be obtained from the published literature (Daponte, Nzewenga, Dimopoulos, & Guidozzi, 2006; Daskalakis et al., 2004; Dickinson, 2005; Morris et al., 2017; Zwerling et al., 2024).
Expert opinion supports:
- No change in medical abortion regimen for people with one uterine scar whose gestation is less than 22-24 weeks.
- After 22-24 weeks gestation with a single uterine scar or 13-24 weeks gestation with more than one uterine scar:
- Consider decreasing the dose of misoprostol with or without lengthening the dosing interval (Ho et al., 2007; Küçükgöz Güleç et al., 2013).
There is insufficient evidence to know if changing the dosing regimen will decrease the risk of uterine rupture.
References
Cetin, C., Buyukkurt, S., Seydaoglu, G., Kahveci, B., Soysal, C., & Ozgunen, F. T. (2016). Comparison of two misoprostol regimens for mid-trimester pregnancy terminations after FIGO’s misoprostol dosage recommendation in 2012. The Journal of Maternal-Fetal & Neonatal Medicine, 29(8), 1314-1317.
Daponte, A., Nzewenga, G., Dimopoulos, K. D., & Guidozzi, F. (2006). The use of vaginal misoprostol for second-trimester pregnancy termination in women with previous single cesarean section. Contraception, 74(4), 324-327.
Daskalakis, G. J., Mesogitis, S. A., Papantoniou, N. E., Moulopoulos, G. G., Papapanagiotou, A. A., & Antsaklis, A. J. (2004). Misoprostol for second trimester pregnancy termination in women with prior caesarean section. BJOG: An International Journal of Obstetrics & Gynaecology, 112(1), 97-99.
Dickinson, J. E. (2005). Misoprostol for second-trimester pregnancy termination in women with a prior cesarean delivery. Obstetrics & Gynecology, 105(2), 352-356.
Goyal, V. (2009). Uterine rupture in second-trimester misoprostol-induced abortion after cesarean delivery: A systematic review. Obstetrics & Gynecology, 113(5), 1117-1123.
Henkel, A., Miller, H. E., Zhang, J., Lyell, D. J., & Shaw, K. A. (2023). Prior Cesarean Birth and Risk of Uterine Rupture in Second-Trimester Medication Abortions Using Mifepristone and Misoprostol: A Systematic Review and Meta-analysis. Obstetrics & Gynecology, 142(6), 1357.
Ho, P. C., Blumenthal, P. D., Gemzell-Danielsson, K., Gómez Ponce de León, R., Mittal, S., & Tang, O. S. (2007). Misoprostol for the termination of pregnancy with a live fetus at 13 to 26 weeks. International Journal of Gynecology & Obstetrics, 99(2), 178-181.
Küçükgöz Güleç, Ü., Urunsak, I. F., Eser, E., Guzel, A. B., Ozgunen, F. T., Evruke, I. C., & Buyukkurt, S. (2013). Misoprostol for midtrimester termination of pregnancy in women with 1 or more prior cesarean deliveries. International Journal of Gynecology & Obstetrics, 120, 85-87.
Latta, K., Barker, E., Kendall, P., Testani, E., Laursen, L., McClosky, L., & York, S. (2023). Complications of second trimester induction for abortion or fetal demise for patients with and without prior cesarean delivery. Contraception, 117, 55–60.
Morris, J. L., Winikoff, B., Dabash, R., Weeks, A., Faundes, A., Gemzell-Danielsson, K., … Visser, G. H. A. (2017). FIGO’s updated recommendations for misoprostol used alone in gynecology and obstetrics. International Journal of Gynecology & Obstetrics, 138(3), 363-366.
Pongsatha, S., Suntornlimsiri, N., & Tongsong, T. (2024). Comparing the outcomes of termination of second trimester pregnancy with a live fetus using intravaginal misoprostol between women with and without previous cesarean section. BMC Pregnancy and Childbirth, 24, 274.
Shakir, H.M. (2022). Safety of vaginal misoprostol for the termination of second trimester miscarriage in women with previous uterine scar in Iraq. Archives of Razi Institute, 77(1), 199-204.
Torriente, M. C., Steinberg, W. J., & Joubert, G. (2017). Misoprostol use for second-trimester termination of pregnancy among women with one or more previous cesarean deliveries. International Journal of Gynecology & Obstetrics, 138, 23-27.
Zwerling, B., Edelman, A., Jackson, A., Burke, A., & with the assistance of Prabhu, M. (2024). Society of Family Planning Clinical Recommendation: Medication abortion between 14 0/7 and 27 6/7 weeks of gestation: Jointly developed with the Society for Maternal-Fetal Medicine. Contraception, 129.