Strengths and Limitations
A strength of our study was the use of equally sized decile groups for the analysis within our initial cohort analysis as opposed to comparing groups by various QBL cutoffs. This allowed us to find an initial inflection range of clinical significance in a less statistically arbitrary manner. Furthermore, as a hospital that was an early participant in the implementation of obstetric hemorrhage bundles, we are able to assess QBL results versus clinically important morbidities in a system with a standardized hemorrhage response. Finally, a strength of our study was the use of data measured using quantitative blood loss methods; most prior existing data informing clinical practices used blood loss quantified by visual estimation, which has been shown to significantly underestimate large volume blood loss by as much as 33-50% when compared to direct or quantitative measurement.9-12 Visually estimated blood loss is thus a poorly defined, inaccurate, and unreliable means of measuring morbidity associated with obstetrical bleeding.
Our study also has limitations. We did not create any adjusted models that would account for possible confounding factors that may impact either total blood loss or baseline risk for morbid outcomes. Future studies should consider stratifying results by factors such as delivery mode and underlying co-morbidities. We were also limited by only two years of data analyzed from a single institution with a population that may not have outcomes that are generalizable to all birthing people. However, as other institutions start to incorporate the use of postpartum hemorrhage bundle protocols that include the utilization of QBL, there is a great opportunity to replicate this data in the future with larger multi-site cohorts.