The Differential Role of Anesthetic Technique by Etiology of Postpartum Hemorrhage: A Dual-Cohort Analysis of Emergency Cesarean Delivery and Placenta Accreta Spectrum

Objective Based on the hypothesis that the effect of general anesthesia (GA) versus neuraxial anesthesia (NA) on postpartum hemorrhage (PPH) varies according to its underlying etiology, this study aimed to investigate the impact of the anesthetic technique on the risk of severe PPH in two distinct clinical scenarios: (1) emergency cesarean deliveries at risk for uterine atony and (2) cases of placenta accreta spectrum (PAS) at risk for massive surgical hemorrhage. Methods In this retrospective dual-cohort study, patients receiving general anesthesia (GA) in Cohort 1 (atony risk) were matched 1:3 to patients receiving neuraxial anesthesia (NA) using propensity score matching (PSM) to control for baseline confounders. Cohort 2 comprised patients with placenta accreta spectrum (PAS) who underwent scheduled cesarean hysterectomy. The primary endpoint was the incidence of severe postpartum hemorrhage (PPH), defined as a composite result of quantitative blood loss > 1500 mL, transfusion of ≥ 2 units of packed red blood cells, or the need for an invasive hemostatic procedure. Results In the matched Cohort 1 (n = 600), the incidence of severe PPH was significantly higher in the GA group compared to the NA group (21.3% vs. 9.8%). After adjusting for operative duration and tranexamic acid use, GA was independently associated with an almost threefold increased risk of severe PPH (Adjusted Odds Ratio [aOR]: 2.91; 95% Confidence Interval [CI]: 1.80–4.69; p < 0.001). In contrast, in Cohort 2 (n = 75), the rate of severe PPH was high in both groups, with no significant difference observed (91.1% vs. 86.7%; p > 0.05). However, a post-hoc Bayesian analysis indicated a high probability (91%) that GA is associated with increased blood loss. Conclusion In our matched cohort, general anesthesia was associated with an almost threefold increase in the risk of severe PPH in emergency cesarean deliveries susceptible to uterine atony (aOR 2.91). In cases such as the placenta accreta spectrum, the primary determinant of hemorrhage is the underlying surgical pathology, and the role of anesthetic management appears to be secondary. However, these findings should be considered exploratory due to the limited statistical power of the cohort. In general, these results strongly support the personalization of anesthetic strategies based on the expected etiology of hemorrhage to reduce maternal morbidity and mortality.