Evaluation of blood transfusion rates by blood loss estimation techniques

Abstract

Background Postpartum hemorrhage is a major cause of maternal morbidity and mortality. Though the American College of Obstetricians and Gynecologists and quality improvement initiatives recommend the use of a quantitative measurement of blood loss, it is not known if the quantitative measurement compared to visual estimation of blood loss improves maternal outcomes. Objective To compare rates of red blood cell transfusion between a quantitative measurement and visual estimation of blood loss. Study design This was a retrospective cohort study of all women who underwent cesarean delivery at a single academic institution from January 2012 to June 2018. Women were excluded if they received a preoperative transfusion or had missing data. Our institution implemented a quantitative measurement of blood loss in September 2015. Our primary outcome was red blood cell transfusion (intraoperative or postoperative). Women who had the quantitative measurement of blood loss (October 2015 to June 2018) were compared with those who had a visual estimation of blood loss (January 2012 to August 2015). Coarsened Exact Matching with a k-to-k solution was performed using predefined variables. Results In total, 4068 had a visual estimation of blood loss and 3117 had the quantitative measurement of blood loss; 1101 women with the quantitative measurement of blood loss were matched to 1101 women with a visual estimation of blood loss. In the unmatched cohort, women who had the quantitative measurement of blood loss compared to those who had a visual estimation of blood loss were more likely to have an increased amount of blood loss (734 ml vs. 700 ml, p < .001) and red blood cell transfusion (7.2% [223/3117] vs. 5.4% [221/4068]; crude odds ratio 1.34; 95% confidence interval 1.11–1.63). This increase in the amount of blood loss (717 ml vs. 700 ml, p < .05) and the rate of red blood cell transfusion (4.5% [49/1101] vs. 2.7% [30/1101]; crude odds ratio 1.66; 95% confidence interval 1.05–2.64) remained statically significant after matching. Conclusion Women who had the quantitative measurement compared with those who had a visual estimation of blood loss were more likely to have an increased amount of blood loss and red blood cell transfusion.