DP24: IMPACT OF HEMOGLOBIN INCREASES ON ALLOWABLE BLOOD LOSS AND TRANSFUSION NEEDS DURING CESAREAN DELIVERIES
Jean-Paul Russo, MPH; Giselle de la Rua, BS; Anthony Rios, BS; YanYun Wu, MD, PhD; Michelle Fletcher, MD; Paloma Toledo, MD, MPH, FASA
University of Miami, Miller School of Medicine
Introduction/Background: The incidence of severe maternal morbidity (SMM) and mortality have been increasing, with postpartum hemorrhage (PPH) as a leading contributor to both. Hemorrhage-related morbidity includes the risk of receiving a blood transfusion, as well as end-organ damage to the patient, and loss of future fertility if a hysterectomy is performed. Poor outcomes in PPH are highly preventable and amenable to safety interventions. Women who are anemic have worse PPH-related outcomes due to their diminished reserve, but antepartum anemia is a modifiable risk factor for preventing adverse outcomes such as peripartum blood transfusions. The concept of allowable blood loss (ABL) calculates the amount of blood which could be lost before a transfusion is necessary based on a patient’s starting hemoglobin. We hypothesized that increasing a patient’s preoperative hemoglobin by 1 g/dL could reduce transfusion rates during cesarean deliveries by expanding allowable blood loss.
Methods: In this retrospective study at Jackson Memorial Hospital, electronic medical record data from 25 anemic women undergoing cesarean deliveries who received a blood transfusion was abstracted. Data extracted included patient’s starting hemoglobin, weight, hemorrhage risk (low, medium, high), intraoperative blood loss, and transfusion data. ABL was calculated for each patient using the following formula:
The EBV was calculated using a pregnancy-adjusted blood volume and the patient’s weight. For patient’s whose body mass index (BMI) was > 30 kg/m2, 65 kg was used for the body weight instead of the actual weight.
The ABL was then calculated with a 1-point higher hemoglobin (Hb +1) and also with a fixed hemoglobin of 10 g/dL (Hb10). Avoidable transfusion was defined as transfusions where the allowable blood loss was less than the actual blood loss. The Kruskal-Wallis test was performed due to non-normally distributed data, conducted via Stata, to assess differences across PPH risk group.
Results: Preoperative hemoglobin varied significantly by PPH risk (P = 0.04), with a mean of 8.05 g/dL (range 7.5–10.9 g/dL). A 1-point increase in hemoglobin would have prevented transfusions in 92% of cases (23/25 women), while a hemoglobin of 10 g/dL would have prevented transfusions in 96% of cases (24/25 women). The allowable blood loss increased with a one-point Hb increase as well as if the theoretical starting Hb was 10 and all patients would have tolerated a postpartum hemorrhage (blood loss of 1000 mL). There were no differences in ABL by PPH risk if the Hb was greater by 1 g/dL or Hb of 10 (Table).
Discussion/Conclusion: A one point increase in patient’s Hb could potentially have avoided 92% of transfusions, and a Hb of 10, while still anemic, could potentially have avoided 96% of transfusions in this cohort. The high transfusion avoidance rates based on adjusted ABL values indicate that modest hemoglobin increases could pose a practical strategy to reduce maternal risks. This study highlights the clinical relevance of optimizing hemoglobin levels to reduce transfusion rates during cesarean deliveries, supporting the potential efficacy of screening and managing iron deficiency in the peripartum period to expand ABL and minimize transfusion risks.
