993: Quantitative blood loss: A potential screening tool to prevent unnecessary postpartum blood draws

Abstract

Visual estimation of blood loss (EBL) is an imprecise method to identify severity of postpartum hemorrhage ( pph). It is a common practice to obtain routine postpartum (PP) CBCs even when clinical suspicion for pph is low, to screen for anemia requiring intervention. We sought to determine whether quantified blood loss (QBL) correlates with PP hematocrit(hct) and is there a cutoff that can be used as a screening tool to predict the need for obtaining PP hct. We conducted a prospective pilot cohort study to ascertain the correlation between QBL and PP hct in low risk pregnancy. A CBC was obtained on admission, postpartum day 1 (PPd1), and postpartum day 2 (PPd2) for all women. Blood loss during delivery was objectively quantified to determine the QBL for each delivery. Paired t-test analysis compared PPd1 and PPd2 hct levels to determine optimal timing of hct levels. Correlation analyses were performed to assess the interdependence of QBL and the absolute change in hct. Multivariable regression was performed to control for potential covariates. A receiver operator curve (ROC) was used to assess the QBL cutoff predictive of an hct level of 25% or less, the hct level chosen as a proxy for PP blood transfusion requirement. A total of 100 women were included in the study, none of them had any significant medical comorbidities. Mean hct on admission was 35.5%. There was no significant difference between mean hct on PPd1 and PPd2 (31 3.4vs. 31 3.8 respectively; p=0.37). QBL was negatively correlated with ppd1 (p< 0.001) and ppd2 (p< 0.001) hct levels and had a strong positive correlation with the absolute change in PP hct levels (p< 0.001). Results were unchanged after controlling for intravenous fluid administration (p=0.002). QBL of 600 mL had a 100% sensitivity and 52% specificity for predicting an hct level ≤25% with an AUC 0.79 [95% CI (0.58 – 0.99)]. QBL is a strong predictor of PP hct. A QBL 600 mL can serve as a potential screening tool to determine the need for obtaining PP hct. Larger prospective studies are needed to assess the validity of this screening tool.View Large Image Figure ViewerDownload Hi-res image Download (PPT)