Evaluation of Risk-Assessment Tools for Severe Postpartum Hemorrhage in Women Undergoing Cesarean Delivery.

Objective: To examine and compare the validity of three known risk-assessment tools (CMQCC [California Maternal Quality Care Collaborative], AWHONN [Association of Women's Health, Obstetric and Neonatal Nurses], and NYSBOH [New York Safety Bundle for Obstetric Hemorrhage]) in women undergoing cesarean delivery.
Methods: We conducted a retrospective cohort study that evaluated all women undergoing cesarean delivery at 23 weeks of gestation or longer from 2012 to 2017 at an urban hospital with average of 1,200 cesarean deliveries per year. Data were obtained by chart review. Severe postpartum hemorrhage was defined as transfusion of at least four units of packed red blood cells during the intrapartum or postpartum period. For each risk-assessment tool, women were stratified into low-risk, medium-risk, and high-risk groups. Risk factors were examined using multivariable logistic regression.
Results: Of 6,301 women who underwent cesarean delivery, a total of 76 (1.2%) had severe postpartum hemorrhage. Women classified as low- or medium-risk had lower rates of severe postpartum hemorrhage (0.4-0.6%) compared with women classified as high-risk (1.8-5.1%) (P<.001). Risk factors that were included in all three tools that were associated with severe postpartum hemorrhage included placenta accreta, placenta previa or low-lying placenta, placental abruption, hematocrit less than 30%, and prior uterine scar. Factors included in only one or two tools that were associated with severe postpartum hemorrhage included having more than four previous vaginal deliveries (CMQCC and AWHONN), stillbirth (AWHONN), and more than four prior births (NYSBOH). Area under the curve and 95% CI for CMQCC, AWHONN, and NYSBOH were all moderate-CMQCC 0.77 (0.71-0.84), AWHONN 0.69 (0.65-0.74), and NYSBOH 0.73 (0.67-0.79), respectively (AWHONN being most sensitive [88% with high-risk as cut-off] and CMQCC being most specific [87% with high-risk as cut-off]).
Conclusions: Risk-assessment tools had moderate prediction to identify high-risk groups at risk for severe postpartum hemorrhage after cesarean delivery.