156: Prediction of red blood cell transfusion after cesarean delivery according to blood loss measurement techniques

Abstract

To identify the blood loss measurement technique that best predicts need for red blood cell (RBC) transfusion after cesarean delivery (CD) and to define the amount of blood, by technique, that predicts RBC transfusion. This was a retrospective review of a quality improvement initiative of all women with singleton pregnancies who underwent CD at >=34 weeks’ gestation between July 1, 2017 and June 30, 2018 at MedStar Washington Hospital Center. Women were eligible to have blood loss measured by visually estimated blood loss (EBL), gravimetric quantitative blood loss (QBL), Gauss Surgical’s Triton ipad application (TBL) and a 24-hour postoperative complete blood count evaluation. Women with multifetal gestation, hypertensive disease and magnesium or anti-hypertensive treatment were excluded. The primary outcome was RBC transfusion. Receiver- operating characteristic curves with area under the curves (AUC) for RBC transfusion by blood loss measurement techniques were created by EBL, QBL and TBL. Blood loss volumes that best predict RBC transfusion were estimated according to blood loss measurement techniques. The secondary outcome included blood loss volumes that best predict RBC transfusion as estimated by measurement technique. We performed a secondary analysis after excluding women with preoperative hemoglobin <10 g/dL. Of the 444 women meeting inclusion criteria, 21 (4.7%) received RBC transfusion. Women who received RBC transfusion compared to women without RBC transfusion were more likely to have higher gravidity, intravenous fluid infusion, EBL, QBL, TBL, and lower preoperative hemoglobin levels (all P <.05). All blood loss measurement techniques had high AUC (EBL 0.87 [95% CI 0.79-0.96], QBL 0.86 [95% CI 0.79-0.93] and TBL AUC 0.90 [95% CI 0.86- 0.99]) (Figure). However, there were no statistical differences among blood loss measurement techniques (P=.22). Blood loss volumes that best predict RBC transfusion by EBL, QBL and TBL are 850 mL, 915 mL, and 643 mL, respectively, with high sensitivity and specificity (Table). After excluding women with preoperative hemoglobin <10 g/dL, the results remained consistent. Blood volume predictive of RBC transfusion in women with CD was dependent on the measurement technique used and did not reflect standard blood loss criteria for postpartum hemorrhage (PPH). PPH defined by >1000 mL of blood loss may underestimate the need for transfusion for some women undergoing CD.View Large Image Figure ViewerDownload Hi-res image Download (PPT)