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Q&A

Clinical Obstetrics

Poster Session 2

(417) Does the allowable blood loss calculator predict postpartum blood transfusion?

Tuesday, February 13, 2024
3:30 PM – 5:00 PM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level

    Primary & Presenting Author(s)

  • Alexa L. Cohen, MD

    Fellow
    Montefiore Medical Center, Albert Einstein College of Medicine
    Bronx, NY, United States

    • Coauthor(s)

  • OO

    Osaro Obanor, MD

    Montefiore Medical Center, Albert Einstein College of Medicine
    New York, NY, United States

  • MP

    Marlena Plagianos, MS

    Population Council's Center for Biomedical Research
    New York, NY, United States

  • SG

    Samantha Goulding, BS, MPH

    Albert Einstein College of Medicine
    New York, NY, United States

  • CP

    Carly Pickett, BS, MSc

    Albert Einstein College of Medicine
    New York, NY, United States

  • BL

    Beatrice Lynch, BS

    Albert Einstein College of Medicine
    New York, NY, United States

  • Pe'er Dar, MD

    Professor and Director, Division of Fetal Medicine
    Montefiore Medical Center, Albert Einstein College of Medicine
    New York, NY, United States

  • Georgios Doulaveris, MD

    Assistant Professor
    Montefiore Medical Center, Albert Einstein College of Medicine
    Bronx, NY, United States

  • MP

    Melissa Peskin-Stolze, MD

    New York University Grossman Long Island School of Medicine
    New York, NY, United States

Objective: The allowable blood loss (ABL) calculator is a patient specific computation used in surgery, trauma and pediatrics that determines at what surgical blood loss transfusion should be considered. This calculator has not yet been studied in the obstetric population. The aim of this study was to investigate if the ABL calculator accurately predicted postpartum blood transfusion in obstetric patients with postpartum hemorrhage (PPH).

Study Design: This retrospective cohort study included all gravidas with PPH at our regional perinatal referral center between January 2020 – December 2022. Patients with BMI > 40kg/m2 were excluded. PPH was defined as quantitative blood loss (QBL) > 1L within 24 hours of delivery. ABL calculation is based on patient’s weight, hemoglobin and average blood volume, with a threshold hemoglobin of 7.0g/dl. The primary outcome was the performance of ABL to predict the need for blood transfusion. We used actual QBL greater than ABL (QBL > ABL) as the threshold for prediction. Sensitivity, specificity, and positive and negative predictive values of QBL > ABL were determined using actual transfusion as the gold standard. Chi-square test and unpaired student t-test were used to compare categorical and continuous variables, respectively. Multivariable logistic regression analysis was also performed.

Results: Overall, 1387 patients met inclusion criteria. Of them, 504 (36.3%) received a blood transfusion. The predictive performance of the QBL > ABL calculation for requiring blood transfusion in gravidas with PPH is presented in Table 1. The positive predictive value for transfusion requirement was 91% (table 1). Gravidas with a QBL > ABL were 21.66 times more likely to be transfused compared to those with a QBL less than ABL, after adjusting for potential confounders (95% CI 9.731 – 48.2, p < 0.01). 

Conclusion: ABL calculation can assist in predicting the need for blood transfusion requirement in gravidas with PPH.