Selective Postoperative Hemoglobin Testing After Cesarean Delivery: A Predictive Model for Severe Postpartum Anemia.

INTRODUCTION

Cesarean delivery is one of the most common surgeries in the United States and is associated with greater postpartum blood loss than vaginal delivery. Despite increasing emphasis on selective, symptom-driven evaluation, routine postoperative hemoglobin testing following cesarean delivery remains common practice. Identifying patients at greatest risk for severe postpartum anemia may help guide more targeted laboratory assessment while avoiding unnecessary testing in low-risk individuals. This study aimed to develop and evaluate a predictive model for severe postpartum anemia following cesarean delivery.

METHODS

We conducted a retrospective cohort study of patients undergoing cesarean delivery at three hospitals within the WakeMed Health and Hospitals system in North Carolina during 2019. Patients aged ≥18 years with both preoperative and postoperative hemoglobin measurements were included. Demographic, obstetric, and clinical variables were extracted from the electronic health record. Severe postpartum anemia was defined as postoperative hemoglobin <7 g/dL. Elastic net logistic regression with 10-fold cross-validation was used to identify predictors of severe anemia.

RESULTS

A total of 2,061 patients met the inclusion criteria. Severe postpartum anemia occurred in 80 patients (3.8%), and 116 patients (5.6%) received blood transfusion. The final predictive model retained two variables: preoperative hemoglobin level and number of uterotonic agents administered. The model demonstrated strong discrimination for predicting severe anemia (area under the curve: 0.89). Applying a prevalence-based probability threshold of 3.5% reduced postoperative hemoglobin testing by 65% while maintaining 90% sensitivity for identifying severe anemia.

DISCUSSION: These findings suggest that a small number of routinely available clinical factors can effectively identify patients at increased risk for severe postpartum anemia following cesarean delivery. A risk-based approach to postoperative laboratory evaluation may support current guideline recommendations favoring selective testing and may reduce unnecessary laboratory utilization without compromising patient safety.

CONCLUSION

A predictive model incorporating preoperative hemoglobin level and uterotonic use provides a simple method for identifying patients at the highest risk for severe postpartum anemia after cesarean delivery. Implementing selective postoperative hemoglobin testing based on risk stratification may improve resource utilization and streamline postpartum care.