(952) Establishing blood loss thresholds predictive of transfusion at the time of delivery

Friday, January 31, 2025

4:00 PM – 6:00 PM

Submitting Author and Presenting Author(s)

Alesha M. White, MD (she/her/hers)

Fellow
University of Texas Southwestern Medical Center
Dallas, Texas, United States

Coauthor(s)

Kristina Fin, MD (she/her/hers)

University of Texas Southwestern Medical Center
Dallas, Texas, United States
JP

Jessica E. Pruszynski, PhD

University of Texas Southwestern
Dallas, Texas, United States
RB

R. Nicholas Burns, MD

Assistant Professor
University of Texas Southwestern
Dallas, Texas, United States
Anne M. Ambia, MD

Assistant Professor
University of Texas Southwestern
Dallas, TX, United States
BA

Brenda Anyaehie, MD

University of Texas Southwestern Medical Center
Dallas, Texas, United States
Elaine L. Duryea, MD

Associate Professor
University of Texas Southwestern Medical Center
Dallas, Texas, United States

Objective: In 2014, the American College of Obstetricians and Gynecologists established a standardized definition of postpartum hemorrhage (PPH) to be blood loss greater than 1000mL from any form of delivery. Prior to this in 1965, Pritchard established the definition of normal blood loss for spontaneous vaginal deliveries (SVD) to be 500mL and for cesarean deliveries (CD) to be 1000mL. Our objective was to establish blood loss thresholds at the time of delivery as they relate to transfusion using quantitative blood loss (QBL).

Study Design: This is a prospective observational study conducted from November 2023 until March 2024 at a single institution that included all SVDs and CDs at which QBL was collected. QBL was calculated and recorded in the electronic medical record by the nursing team, but not reported to providers, who used estimated blood loss (EBL) and clinical indices to guide clinical care, per existing practices. Receiver operating characteristic (ROC) curves were generated based on the probability of transfusion.

Results: QBL data was available for 4,543 deliveries. 3,236 (71%) of total deliveries were via SVD and 1,234 (27%) of deliveries were via CD. Based on an ROC curve for SVDs, the optimal cut point for transfusion was determined to be 449.5mL. This represented a sensitivity of 71% and a specificity of 79% with an AUC of 0.81. Based on an ROC curve for CDs, the optimal cut point for transfusion was determined to be 1012.5mL. This represented a sensitivity of 61% with a specificity of 72% and an AUC of 0.7. The prevalence of transfusion at each respective cut point for type of delivery represented a 10.90% prevalence of transfusion for CDs and a 4.60% prevalence of transfusion for SVDs.

Conclusion: The QBL cut points associated with transfusion in this study are very similar to prior cut points determined to represent normal blood loss at delivery, which is known to differ by mode of delivery. Such that, not all deliveries should be classified as normal based on a 1000mL cut point alone and a heightened awareness should be present when QBL exceeds 500cc for SVD.