A model to predict red blood cell transfusion during/after cesarean delivery

Cesarean delivery is a major risk factor for postpartum hemorrhage. A priority for postpartum hemorrhage safety bundles is the assessment of hemorrhage and transfusion risk following cesarean delivery and the identification of patients at increased risk for postpartum hemorrhage requiring red blood cell transfusion. A prediction model based on antenatal and intrapartum risk factors could be used in a standardized manner among all patients when considering crossmatch or other preparatory measures prior to cesarean delivery.

To develop a multivariable prediction model for red blood cell transfusion associated with cesarean delivery using a prospective contemporary cohort.

Secondary analysis of a multicenter trial of tranexamic acid (TXA) versus placebo for the prevention of red blood cell transfusion after cesarean delivery was performed. The primary outcome for this analysis was transfusion of packed red blood cells by hospital discharge or 7 days postpartum, whichever came first. Maternal characteristics and risk factors related to labor were compared between patients who received a transfusion and those who did not. Any of the characteristics that differed with a p value <0.05 were considered in a multivariable model. Model selection and internal validation were performed using k-fold cross-validation. Using backward elimination, variables that remained significant at p < 0.05 were retained in each model. The final model was chosen based on the highest area under the receiver operating characteristic curve (ROC) in the validation set.

A total of 418 of 10,961 patients (3.8%) received a red blood cell transfusion. Factors associated with transfusion and retained in the final model included gestational age at delivery <34 weeks or ≥41 weeks, chorioamnionitis, aspirin use in the week before delivery, preoperative hemoglobin level, preoperative platelet count <100,000, oxytocin duration, and cesarean delivery during the second stage of labor. The final multivariable model had excellent discrimination with an area under the curve (AUC) of 0.79 (95% confidence interval [CI], 0.76, 0.81). Using the same set of seven factors identified in the prediction model for transfusion, the AUC was 0.62 (95% CI, 0.60, 0.65) for differentiating patients who did and did not require surgical/radiological interventions in response to bleeding.

We identified several factors associated with risk of red blood cell transfusion during/after cesarean delivery and a model with excellent predictive ability. Risk factors in this model, including lower preoperative hemoglobin level, aspirin use <7 days before delivery, and delivery during the second stage of labor, may be used to risk-stratify patients for preparation for transfusion to reduce postoperative complications that result from bleeding.