838 A comparison of estimated and quantitative blood loss for cesarean and vaginal deliveries

Abstract

Both visual estimates and quantitative measurements are routinely used to assess maternal blood loss during deliveries. We sought to investigate differences between estimation and quantification of maternal blood loss for cesarean (CD) and vaginal deliveries (VD). In this retrospective chart review, blood loss from all births between January 1, 2017 and June 30, 2020 at a tertiary care center were analyzed by mode of delivery. By institutional convention, visually estimated blood loss (EBL) was recorded in 50 mL intervals. Quantified blood loss (QBL) was generated by the Triton L&D System for volumetric and gravimetric estimation of blood loss for VD and image analysis of sponges and suction canister content in CD. If QBL ended in a multiple of 50, 1 mL was added to distinguish EBL from QBL. Records without blood loss or delivery mode recorded, and instances of severe hemorrhage (>1500mL) were excluded. Kruskal-Wallis rank sum tests were performed as appropriate. 22,108 deliveries were identified. 1,595 and 20 patients were excluded for missing blood loss and delivery method respectively. 533 patients with severe hemorrhage were excluded (Skewness 7.01 prior to exclusion). The remaining 19,960 patients were included for analysis. For vaginal deliveries, median quantified blood loss was 343mL (IQR 201 to 537), whereas estimated blood loss was 300mL (IQR 200 to 400, p<0.001). For cesarean deliveries, median quantified blood loss was 410mL (IQR 260 to 718), and estimated blood loss was significantly higher at 800mL (IQR 600 to 800, p<0.001). QBL has been proposed as a method to achieve more accurate quantification of blood loss to better guide interventions to prevent hemorrhage and severe maternal morbidity. Assuming higher fidelity of QBL, our results indicate overestimation of blood loss for CD and underestimation of blood loss for VD using traditional visual estimates. However, QBL methods may indeed be underestimating blood loss in CD given the nearly 400mL difference in medians. Further research is necessary to evaluate the impact of QBL on clinical outcomes.View Large Image Figure ViewerDownload Hi-res image Download (PPT)