October 17, 2026
Prehospital transfusion is expanding rapidly, with the number of programs exceeding 450. But as prehospital transfusion becomes more widespread, variability in data collection and the clinical considerations involved in treating special patient populations present important challenges.
At Saturday’s AABB/THOR joint session, speakers explored efforts to standardize outcome reporting and address the risks and benefits of transfusion in pediatric patients and females of childbearing potential.
Matthew J. Levy, DO, MSc, FAEMS, FACEP, chief medical officer of the Howard County Department of Fire and Rescue Services and Howard County Police Department, kicked off the session with a discussion of the Standardized EMS Metrics for Survival in Transfusion and Advanced Resuscitation (SEMSTAR) framework.
SEMSTAR is the first national, consensus-driven effort to establish standardized data elements and definitions for reporting outcomes in emergency medical services transfusion programs. Without agreed-upon definitions, he explained, a program’s reported survival rate can be difficult to interpret because programs may differ in which patients they include. Standardization is essential for benchmarking, quality improvement and research, he said.
The project used a multistage consensus process involving 28 experts and input from 89 EMS systems. It produced 86 core data elements intended for universal reporting and 82 expanded elements for more detailed analysis. Levy emphasized that most elements are already captured in existing data systems, including the National EMS Information System and trauma registries.
The project also established standardized definitions for clinical outcomes. For example, Levy explained that what clinicians often call “trauma arrest” may represent hemorrhagic circulatory collapse. The consensus definition characterizes this as a physiologic state rather than an end state, he said. SEMSTAR also standardized survival reporting at 6, 12, 24 and 72 hours, and at 30 days or hospital discharge, whichever comes first. The SEMSTAR survival measure excludes patients who experienced hemorrhagic circulatory collapse before transfusion, allowing those cases to be evaluated separately.
Levy concluded by emphasizing that SEMSTAR is not a registry itself, but a foundation for building data infrastructure to support consistent reporting and future research.
Phil Spinella, MD, co-director of the Trauma and Transfusion Medicine Center at the University of Pittsburgh, continued with an examination of the clinical considerations involved in treating children with life-threatening bleeding. Although children can compensate physiologically during critical illness, he noted that mortality from life-threatening bleeding is nearly twice as high in children as in adults. He attributed this disparity to delays in recognizing hemorrhagic shock and initiating treatment.
Spinella reviewed two single-center retrospective studies that found an association between whole blood use as part of resuscitation and improved survival in children. He noted that these studies represent the current evidence comparing whole blood with component therapy in pediatric patients, and he stressed that whole blood is typically only one part of these patients’ resuscitation. He added that other studies have associated whole blood use with lower overall blood product utilization.
Spinella also addressed the use of RhD-positive whole blood in girls when RhD-negative whole blood is unavailable. He argued that programs considering whole blood for its potential survival benefit in boys and men should also consider its use in girls and women, while weighing potential clinical benefits against the long-term risk of alloimmunization.
He cautioned that adopting therapies before clinical trials are completed can make it more difficult to establish their efficacy and safety. He cited tranexamic acid use in children, noting that widespread adoption in prehospital programs has limited enrollment in his own pediatric trial.
Jennifer Andrews, MD, MSc, professor of pathology, microbiology and immunology and pediatrics at Vanderbilt University Medical Center, concluded the session with a discussion of the benefits and risks of low-titer group O whole blood, particularly RhD-positive products in females of childbearing potential.
She said whole blood offers logistical advantages in prehospital settings, where space and the availability of multiple blood products may be limited. However, because RhD-negative whole blood is difficult to collect in sufficient quantities, Andrews noted that most women younger than 50 may receive RhD-positive products.
She cited a reported alloimmunization risk of 10% to 40%, depending on factors including age and immune status. The resulting antibodies can pose risks during future pregnancies, including hemolytic disease of the fetus and newborn.
Andrews described a multidisciplinary approach at Vanderbilt that uses automatic notifications, an electronic order set for follow-up antibody screening, referrals and patient education. She emphasized that antibody screening performed before 14 weeks after exposure can produce a false-negative result, making coordinated follow-up important even after patients have left the hospital.
Andrews said early identification of alloimmunization is particularly important because interventions for affected pregnancies may need to begin early. She encouraged institutions to assess their resources and engage transfusion medicine, emergency care and obstetric teams in developing follow-up systems suited to their settings. Andrews also highlighted an AABB toolkit in development to help institutions implement these practices.
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