(1222) Measuring What Matters: The Clinical Utility of Quantitative vs. Estimated Blood Loss in Postpartum Hemorrhage

Objective:
Postpartum hemorrhage (PPH) is a major contributor to maternal morbidity and mortality worldwide. Imprecise estimation of blood loss significantly contributes to preventable PPH-related deaths. Although quantitative blood loss estimation (QBL) is more accurate than visual estimation (EBL), its impact on adverse clinical outcomes remains unclear. This study compares the predictive value of EBL and QBL for postpartum transfusion, the leading cause of maternal morbidity in the United States.

Study Design:

We conducted a retrospective cohort study of all deliveries at a tertiary care center between January 2024 and June 2025. Only individuals with both EBL and QBL recorded were included. The correlation between EBL and QBL was assessed using Spearman correlation. Receiver operating characteristic (ROC) curves were used to compare the predictive value of EBL and QBL for postpartum transfusion. Subgroup analyses were performed based on mode of delivery.

Results:

Among 5,544 individuals, 3,526 (63.6%) met inclusion criteria. Of those included, 145 (4.1%) received a transfusion during admission. The median EBL was 350 mL (IQR 200-700 mL), and the median QBL was 435 mL (IQR 237-800 mL). There was a strong correlation between EBL and QBL, with Spearman’s rho of 0.86 (p< 0.001; Figure 1). PPH defined as blood loss >1000 mL was identified significantly more frequently by QBL than by EBL (15.7% vs 11.7%, p< 0.001). However, EBL and QBL did not differ in their ability to predict transfusion (area under the curve (AUC) 0.90 for both, p=0.52; Figure 2). Subgroup analysis revealed consistent predictive value of QBL and EBL across delivery modes (AUC 0.91 for vaginal delivery for both, p=0.37; AUC 0.81 for EBL and 0.80 for QBL for cesarean section, p=0.81)

Conclusion:

While QBL identifies PPH more frequently than EBL, both methods are similarly strong predictors of the need for transfusion in the postpartum period. Further research is needed to evaluate the clinical utility of QBL versus EBL in reducing maternal morbidity, assessing additional maternal outcomes, and exploring the cost implications of implementing QBL.