Anterior Placentation as a Risk Factor for Hemorrhage at the Time of Primary Cesarean Delivery.

Abstract

Objective: Anterior placentation is a risk factor for hemorrhage during cesarean delivery in patients with a resolved placenta previa or low-lying placenta. As anterior placentas are sometimes incised at the time of hysterotomy, it is possible that, even in the absence of low-lying placenta or placenta previa, anterior placentation may be associated with higher blood loss at the time of nonlaboring, primary cesarean delivery. Therefore, we sought to identify if there is an association between anterior placentation and peripartum hemorrhage (PPH) in parturients undergoing primary cesarean delivery.

Study design: This is a retrospective cohort study that included parturients from a tertiary care center who underwent primary cesarean delivery from 2016 to 2022. Patients with known risk factors for PPH (known placenta accreta spectrum, placenta previa, etc.) were excluded from primary analyses. Primary analyses assessed the association via logistic regression between PPH (defined as estimated blood loss [EBL] ≥ 1,000 mL) and anterior placentation. We then assessed if this risk was present in higher risk subgroups (patients using anticoagulation at the time of delivery and patients who underwent vaginal trial of labor prior to primary cesarean) and a lower risk subgroup (those undergoing nonlaboring primary cesarean).

Results: The primary cohort consisted of 996 parturients. Of those, 501 had an anterior placenta. Odds ratio of EBL ≥ 1,000 according to anterior placentation was 1.12 (95% confidence interval: 0.80-1.56) in multivariate regression. Risk of PPH was not associated with anterior placentation in higher- and lower-risk subgroups.

Conclusion: Anterior placentation alone is not associated with higher EBL in patients undergoing primary cesarean delivery, even in patients using anticoagulation or those requiring intrapartum cesarean.

Key points: · Anterior placenta and previa increase hemorrhage risk.. · Anterior placentation alone does not increase hemorrhage risk.. · The risk is not increased among those with additional risk factors.. · Placenta location may impact hemorrhage risk..