Third-stage uterotonic management after second-trimester induction of labour: a retrospective cohort study

Retained placenta is a potential complication of second-trimester induction of labour. There is limited consensus regarding the use of adjunctive medications to manage the third stage following second-trimester vaginal delivery. This study aimed to evaluate the effects of oxytocin versus misoprostol on third-stage duration and the need for dilation and curettage (D&C) among patients with and without mifepristone pretreatment.

We conducted a retrospective cohort study of patients undergoing induction of labour between 14 + 0 and 23 + 6 weeks of gestation for any indication. Data on third-stage uterotonic use and mifepristone pre-treatment were collected. Primary outcomes were third-stage duration and the need for D&C for retained placenta among patients who received a third-stage uterotonic agent. Associations were assessed using adjusted linear and logistic regression models controlling for relevant clinical covariates.

Among 181 patients, 85 (47.0%) received a third-stage uterotonic (oxytocin n = 55, 30.4%; misoprostol n = 45, 24.9%) and 101 (55.8%) received mifepristone (median 4.6 h prior to induction). Among patients receiving a third-stage uterotonic, oxytocin use was associated with a 2-hour reduction in placental delivery time and a 74% lower likelihood of D&C compared with misoprostol. Mifepristone pretreatment was not associated with third-stage duration (10 vs 24.5 min, p = 0.43) or D&C rates (12.9% vs 13.8%, p = 0.86).

When third-stage uterotonic intervention is required following second-trimester induction of labour, oxytocin is associated with significantly shorter placental delivery time and lower likelihood of D&C when compared with misoprostol. Mifepristone pretreatment shortly before induction appears to have minimal impact on third-stage outcomes.