Introduction of a Novel System for Quantitating Blood Loss After Vaginal Delivery: A Retrospective Interrupted Time Series Analysis With Concurrent Control Group

Abstract

Background: Postpartum hemorrhage (PPH) is a leading cause of maternal mortality worldwide. While volumetric and gravimetric blood loss measurement techniques have been shown to increase PPH detection compared to visual estimation of blood loss (vBL), a combination of these methods has not been evaluated. The primary aim of this study was to compare the change in odds of PPH detection after vaginal delivery (VD; the intervention series) versus cesarean delivery (CD; the control series) before versus after implementation of a device (Triton L&D, Gauss Surgical, Inc, Los Altos, CA) that combines gravimetric and volumetric estimation of blood loss (tBL).

Methods: After institutional review board (IRB) approval, patients were identified who had a VD or CD at our institution 3 months before and 3 months after the implementation of a tBL device for VD. The levels and trends in odds of PPH detection (the primary outcome, defined as blood loss ≥500 mL for VD and ≥1000 mL for CD) were compared within and between delivery methods before and after implementation of the device. Secondary outcomes were blood loss ≥1000 mL, total blood loss, secondary uterotonic use, and a composite outcome related to PPH management (transfusion, vasopressor administration, and/or surgical procedures). A post hoc subgroup analysis compared nadir hematocrit, hematocrit reduction ≥10%, and difference between vBL or tBL and calculated blood loss (cBL) between VDs before and after introduction of the device. All outcome comparisons were performed using segmented regression with inverse probability of treatment weighting.

Results: The weighted odds ratio (wOR) of PPH detection post- versus preimplementation of the device was 2.74 (95% confidence interval [CI], 1.39-5.41; P = .004) for VDs versus 1.43 (95% CI, 0.72-2.85; P = .304) for CDs (P for interaction .190). No difference was detected in the secondary outcomes for VDs between time periods. In the subgroup of VD patients who had postdelivery hematocrits measured, the mean difference between vBL or tBL and cBL was smaller in the tBL (mean ± standard deviation [SD]: -237 ± 522 mL) versus vBL group (-600 ± 596 mL; weighted difference in means [95% CI]: 349 mL [13-684]; P = .042).

Conclusions: In this interrupted time series analysis, the odds of PPH detection after VD increased after implementation of the tBL device. However, a statistical difference was not detected between the increase in PPH detection post- versus preimplementation of the device in VDs versus CDs.