OBJECTIVE: Our goal is to describe the association between total
quantitative blood loss (QBL) and risk of obstetric hemorrhage-related
morbidity (OBH-M) in order to assess utility of the current definition
of obstetric hemorrhage (OBH). DESIGN: Retrospective cohort study.
SETTING: Urban safety-net hospital in Boston, Massachusetts. POPULATION
or SAMPLE: Deliveries at our institution over a two-year period.
METHODS: We categorized deliveries into ten equally sized deciles based
on QBL and compared the proportion with OBH-M in each. Among the two
deciles with the highest proportions of OBH-M, we stratified deliveries
into seven groups of ascending intervals of 250cc QBL. Finally, we
compared the positive predictive value (PPV) of the standard definition
of OBH (QBL ≥ 1000cc) to a definition extrapolated from our stratified
analysis. MAIN OUTCOME MEASURES: The primary outcome was proportion of
deliveries within each QBL decile affected by OBH-M. The secondary
outcome was PPV. RESULTS: We found a significant increase in OBH-M from
decile 9 (895-1201cc QBL) to decile 10 (1205-8325cc QBL)
(p<0.001). In our stratified analysis, we found QBL of 1500cc
to be an inflection point for an increased proportion of OBH-M. Our
secondary analysis showed an increased PPV for OBH-M using QBL of 1500cc
(20.5%) compared to that of QBL 1000cc (9.8%). CONCLUSIONS: Our
findings suggest that a higher QBL threshold than the currently accepted
definition of OBH is more predictive of OBH-M.