Second-line uterotonics and the risk of hemorrhage-related morbidity

Uterine atony is a leading cause of postpartum hemorrhage. Although most cases of postpartum hemorrhage respond to first-line therapy with uterine massage and oxytocin administration, second-line uterotonics including methylergonovine and carboprost are integral for the management of refractory uterine atony. Despite their ubiquitous use, it is uncertain whether the risk of hemorrhage-related morbidity differs in women exposed to methylergonovine or carboprost at cesarean delivery.

We performed a secondary analysis using the Maternal-Fetal Medicine Units Network Cesarean Registry. We identified women who underwent cesarean delivery and received either methylergonovine or carboprost for refractory uterine atony. The primary outcome was hemorrhage-related morbidity defined as intraoperative or postoperative red blood cell transfusion or the need for additional surgical interventions including uterine artery ligation, hypogastric artery ligation, or peripartum hysterectomy for atony. We compared the risk of hemorrhage-related morbidity in those exposed to methylergonovine vs carboprost. Propensity-score matching was used to account for potential confounders.

The study cohort comprised 1335 women; 870 (65.2%) women received methylergonovine and 465 (34.8%) women received carboprost. After accounting for potential confounders, the risk of hemorrhage-related morbidity was higher in the carboprost group than the methylergonovine group (relative risk, 1.7; 95% confidence interval, 1.2-2.6).

In this propensity score-matched analysis, methylergonovine was associated with reduced risk of hemorrhage-related morbidity during cesarean delivery compared to carboprost. Based on these results, methylergonovine may be a more effective second-line uterotonic.