251: Accuracy of colorimetric quantitative blood loss estimation for identification of postpartum hemorrhage

Abstract

Accurate estimated blood loss (EBL) is a core tenet of postpartum hemorrhage (PPH) protocols. Quantitative blood loss (QBL) aims to overcome inaccuracies associated with visual EBL. We compared the accuracy of obstetric EBL for prediction of postpartum hemoglobin (Hgb) changes before and after adoption of a colorimetric QBL system (Triton, Gauss Surgical). Retrospective cohort of deliveries before (“pre-QBL,” 8/2015-2/2017) and after (“post-QBL,” 8/2018- 3/2018) QBL adoption. Deliveries (3/2017-7/2017) were excluded during transition to QBL. Women met inclusion if they delivered at ≥20wks. All pre-QBL deliveries had physician EBL values. In the post-QBL phase, QBL was recorded as a separate value from physician EBL, but physicians were not blinded to the QBL value. The primary outcome was the difference between actual change in Hgb (predelivery Hgb - Hgb 24hrs after delivery) and predicted change in Hgb (predelivery Hgb - predicted Hgb 24hrs after delivery). Differences closer to 0 were more accurate with - and + values reflecting over- and underestimation, respectively. Predicted Hgb values were calculated using EBL, maternal blood volume and predelivery Hgb. Analyses were stratified by mode of delivery and PPH (EBL>1000mL). A secondary analysis compared predicted change in Hgb using pre-intervention EBL values and post -intervention QBL values. Secondary outcomes included composite maternal morbidity (blood transfusion >2 units, embolization, hysterectomy, ICU, exploratory laparotomy, DIC, intubation, kidney injury, and death) and time from PPH to transfusion of blood products. Mean differences between pre-QBL and post-QBL were evaluated with two- sample Student t-tests. There were 9,101 deliveries; 2,753 were post-QBL. Physician EBL was less accurate for prediction of change in Hgb after implementation of QBL in deliveries without PPH (Table 1). QBL values were more accurate than pre- intervention EBL values for prediction of Hgb change among cases of PPH (Table 2). Although less accurate, EBL in cases of PPH was an overestimate of change in Hgb. There was no difference in maternal composite morbidity (9.8 vs 12.3%; p=0.28) or median time to transfusion (17.0 vs 6.3 hours, p=0.51) between pre- and post-QBL. QBL estimates were more accurate in the setting of PPH; however, QBL adoption did not improve morbidity or time to transfusion in our tertiary care center. Analysis of the utility of QBL in other settings is warranted.View Large Image Figure ViewerDownload Hi-res image Download (PPT)