Comparison of three antepartum risk assessment tools to predict significant postpartum hemorrhage in livebirths.

BACKGROUND: To adequately predict significant postpartum hemorrhage (PPH) at hospital admission, we evaluated and compared the accuracy of three risk assessment tools: 1. California Maternal Quality Care Collaborative (CMQCC), 2. American College of Obstetrics and Gynecology Safe Motherhood Initiative (ACOG SMI) and 3. Association of Women's Health, Obstetric and Neonatal Nurses (AWHONN).

STUDY DESIGN AND METHODS: This is a retrospective cohort study of people who delivered liveborn infants from January 2018 to June 2021 at our center. Patients with comorbidities necessitating higher hemoglobin values, those who refused blood transfusions, and missing pertinent data were excluded. Significant PPH was defined as a blood transfusion within 48 hours following delivery. Diagnostic statistics were calculated for each tool.

RESULTS: Of the 11,679 included pregnancies, 232 (1.9%) people had significant PPH. Amongst those diagnosed as high-risk by the CMQCC tool, 67/1485 (4.5%) had significant PPH; 62/1672 (3.7%) by the ACOG SMI tool, and 85/1864 (4.6%) by the AWHONN tool had significant PPH. All tools have low sensitivity and high negative predictive values. The area under the receiver operating characteristics curve of the three tools is moderately poor (CMQCC: 0.58, ACOG SMI: 0.55, AWHONN:0.61).

DISCUSSION: Upon admission to labor and delivery, all three studied tools are poor predictors of significant PPH. The development and validation of better PPH risk stratification tools are required with the inclusion of additional important variables.