Background: Fresh whole blood (FrWB) is routinely used in the resuscitation of combat casualties in Operation Iraqi Freedom and Operation Enduring Freedom. However, studies have shown high rates (20%-40%) of transfusion-associated microchimerism (TA-MC) in civilian trauma patients receiving allogenic red blood cell (RBC) transfusions. We explored the incidence of TA-MC in combat casualties receiving FrWB compared with patients receiving standard stored RBC transfusions. Methods: Prospective data on TA-MC at > ...