Predictors of Postpartum Hemorrhage Following Cesarean Delivery: A Model for Calculating Risk of Transfusion

OBJECTIVE Postpartum hemorrhage (PPH) is one of the leading causes of morbidity and mortality in obstetrics worldwide. There has been an appreciable rise in the severity of PPH requiring more transfusions in the United States. Our objective is to better define patients at greatest risk for severe PPH in order to identify cases for early intervention and monitoring. STUDY DESIGN Using the MFMU Network\u27s Cesarean Registry, we identified cases of PPH defined as 1) non-severe (nsPPH): requiring less than 4 units pRBCs or 2) severe (sPPH): requiring greater than or equal to 4 units pRBCs or ICU admission. We used a reference group of no transfusion (no txf) for comparison. We compared prevalence and severity of hemorrhage associated with maternal, fetal, and socioeconomic risk factors. Multivariate logistic regression models were used to identify predictors that were independently associated with either 1) nsPPH vs no txf, 2) sPHH vs no txf, and 3) any hemorrhage vs no txf. A risk calculator was developed for predicting the need for blood transfusion. RESULTS We included 56,967 women, with 983 cases of nsPPH (1.7%) and 726 cases of sPPH (1.3%). Race was identified as an independent risk factor for all PPH with Asians having the highest risk for hemorrhage (OR 2.02, 95% CI 1.35-3.01), followed by Hispanics (OR 1.47, CI 1.26-1.71) and African Americans (OR 1.25, CI 1.09-1.44). General anesthesia (OR 7.57, CI 6.35-9.02), preeclampsia (OR 2.44, CI 1.66-3.58), greater than 3 prior term deliveries (OR 1.51, CI 1.22-1.88) and failed TOLAC (OR 1.92, CI 1.51-2.25) are significant risk factors for severe PPH. Variables that were found to be protective against sPPH were higher starting hematocrit (OR 0.68, CI 0.64-0.72) and being a term gestation greater than 38 weeks (OR 0.51, CI 0.42-0.61). This model has good discrimination for predicting nsPPH and sPPH with AUC being 0.82 and 0.81, respectively._x000D_ _x000D_ CONCLUSIONÂ _x000D_ Different risk factors exist predisposing women to non-severe and severe PPH among this large cohort who required cesarean section. Using our data, we were able to create a risk calculator for identifying patients at highest risk for postpartum hemorrhage requiring a blood transfusion.With an accurate prediction model, those at risk for severe PPH could be identified prior to delivery leading to interventions to improve patient outcomes through preparedness, preoperative planning, and patient counseling