Impact of hemoglobin increases on allowable blood loss and transfusion needs during cesarean delivery

Severe maternal morbidity and mortality are rising in the United States, with postpartum hemorrhage (PPH) as a major contributor. Addressing antepartum iron deficiency and anemia could potentially prevent complications and mitigate maternal risks. The concept of allowable blood loss (ABL) estimates the blood volume a patient can lose before requiring a transfusion. We hypothesized that a 1 g/dL increase in preoperative hemoglobin (Hb) could increase ABL and lower transfusion rates during cesarean delivery.

Electronic medical records of 25 anemic women who underwent cesarean delivery and received at least one blood transfusion were abstracted. ABL and estimated blood volume (EBV) were calculated based on collected data. ABL was then calculated for two scenarios: a 1-point Hb increase and a fixed Hb of 10 g/dL. Avoidable transfusions were defined as those where the ABL exceeded actual blood loss.

A 1-point increase in Hb would have prevented transfusions in 92% of cases, while a Hb of 10 g/dL would have prevented transfusions in 96% of cases. All patients would have tolerated a postpartum hemorrhage with adjusted values.

This analysis demonstrates that a modest increase in preoperative Hb has the ability to improve ABL and potentially avoid transfusion. The concept of ABL can be applied to define a patient-specific Hb target; therefore, effective management of anemia in the peripartum setting could potentially reduce peripartum transfusions, enhancing maternal outcomes. Future directions should aim to evaluate the clinical impact on transfusion rates and maternal health outcomes.