Direct Comparison of Three Postpartum Hemorrhage Risk Assessment Tools: A Retrospective Secondary Data Analysis

The objective was to compare the performance of three postpartum hemorrhage risk screening tools with a known patient data set.

This is a retrospective secondary data analysis of a parent study whose aim was to develop a novel biomarker for detecting elevated blood loss with childbirth.

A single tertiary care hospital in the United States.

Inclusion criteria for the parent study were ≥ 37 weeks, ≥ 18 years, and pregnancy with one live fetus (no multiples). Eligible participants were identified upon admission to the labor unit and enrolled after informed consent was obtained.

Statistical analyses were computed using Stata SE, v18. Bivariate associations between binary outcomes and continuous measures were calculated using independent t-tests. Bivariate associations between binary outcomes and categorical measures were calculated using chi-square tests.

Recruitment occurred June through September 2021 and included n = 525 participants. When using the American College of Obstetricians and Gynecologists' threshold of ≥ 1000 mL, 13.3% (n = 70) of parturients experienced a hemorrhage. When using the World Health Organization's definition of postpartum hemorrhage of ≥ 500 mL, the prevalence of hemorrhage was 36.8% (n = 193). Sensitivity was highest in identifying hemorrhage with the Association of Women's Health, Obstetric and Neonatal Nurses' tool. When high- and medium-risk scores were considered, the tool had 86% (95% CI: 83.0%-89.0%) accuracy in identifying cases of hemorrhage. This tool also had the highest negative predictive value (78.7%, CI 75.2%-82.2%).

The tool with the highest sensitivity and negative predictive values identified 21% of cases as "low risk" that went on to experience blood loss ≥ 500 mL, thus underscoring the need for better predictive models.