Quantitative Blood Loss in Cesarean Delivery Is More Accurate Than Visual Estimation [ID: 1376884]

INTRODUCTION: The objective of this study was to determine the difference in milliliters between calculated blood loss (CBL) and two measurement techniques: estimated blood loss (EBL) versus quantitative blood loss (QBL) for cesarean deliveries. METHODS: This was a retrospective cohort study at a tertiary hospital examining blood loss from singleton, term cesarean births. EBL and QBL groups contained 6 separate months of deliveries. Measurements were compared to a standard CBL: (0.75 × {[maternal height (inches)×50]+[maternal weight in pounds×25]}) by percent of blood volume lost ({predelivery HCT – postdelivery HCT}/predelivery HCT). Values of CBL − recorded blood loss=0 mL represented a more accurate measurement. Blood product transfusion was also compared. RESULTS: Median CBL did not differ between EBL (n=460) and QBL (n=507) groups: 836 mL (interquartile range [IQR] 566–1,135) versus 839 mL (IQR 608–1,175, P=.363). Reported blood loss was not different between EBL and QBL groups: 700 (IQR 600–800) mL and 677 (IQR 479–981, P=.501) mL, respectively. Differences between the CBL and recorded blood loss was larger in the EBL group (172 [IQR –101 to 474] mL) than the QBL group (−106 [IQR –379 to 118] mL), with P<.001. Transfusion rates did not differ between groups (P=.789). CONCLUSION: The positive value of 172 mL suggests that EBL is an underestimation of CBL, while the negative value of −106 mL suggests QBL is a slight overestimation, although a better approximator of CBL. These data offer insight into quantifiable value differences between EBL and QBL, which may be used in future investigation to adequately power studies that evaluate blood measurements techniques and influences on clinical decision-making.