Single-unit vs multiple-unit transfusion in hemodynamically stable postpartum anemia: a pragmatic randomized controlled trial.

Background: The American Academy of Blood Banks recommends single-unit red cell transfusion protocols across medicine to reduce transfusion complications and the use of a scarce resource. There are minimal data regarding single-unit protocols in obstetrics.

Objective: We aimed to compare single-unit vs multiple-unit transfusion protocols for treatment of hemodynamically stable postpartum anemia.

Study Design: We performed a randomized trial comparing initial transfusion with 1 unit of packed red blood cells (single-unit protocol) to 2 units of packed red blood cells (multiple-unit protocol) from March 2018 to July 2019. Women who required transfusion >6 hours postpartum were approached for consent. Unstable vital signs, hemoglobin level <5 g/dL, hemoglobinopathy, and cardiomyopathy were exclusion criteria for enrollment. Hemoglobin assessment and standardized clinical evaluation were performed 4 to 6 hours posttransfusion; additional packed red blood cells were given if indicated. The primary outcome was total units transfused. Secondary outcomes included length of stay, endometritis, wound separation or infection, venous thromboembolism, and intensive care unit admission within 30 days postpartum. Breastfeeding, depression, maternal attachment, and fatigue scores were assessed at 4 to 9 weeks postpartum. A total of 66 women were required to detect a 20% reduction in units transfused with a single-unit protocol (power=80%; α=0.05).

Results: A total of 66 women were randomized (33 per arm). There were no differences between groups in demographic or clinical characteristics, including delivery mode, blood loss, and randomization hemoglobin levels. The mean number of units transfused was lower in the single-unit protocol than in the multiple-unit protocol (1.2 U vs 2.1 U; P<.001). Only 18.2% of women in the single-unit arm required additional packed red blood cells. At posttransfusion assessment, women in the single-unit arm had lower hemoglobin levels (7.8 g/dL vs 8.7 g/dL; P<.001), but there were no differences in vital signs or symptoms between groups. There were also no differences in length of stay, 30-day complications, or 4 to 9 week postpartum outcomes.

Conclusion: In women with hemodynamically stable postpartum anemia, a single-unit protocol avoided a second unit of packed red blood cells in >80% of women without significant impact on morbidity. Our work supports the use of single-unit initial transfusion in this population.