Emergency uncrossmatched transfusion effect on blood type alloantibodies.

BACKGROUND: Trauma patients receive emergency transfusions of unmatched Type O Rh-negative (Rh-) blood until matched blood is available. We hypothesized that patients given uncrossmatched blood may develop alloantibodies, placing them at risk for hemolytic transfusion reactions (HTRs). METHODS: Data regarding alloantibody profiles and HTR occurrence were collected from the records of trauma patients at our university-based trauma center who received emergency uncrossmatched blood from July 2008 to August 2010. RESULTS: A total of 132 patients received 1,570 units of packed red blood cells. Mean injury severity score was 28 ± 1.3. Forty-five (34%) patients died: 27 on hospital day 1; the remaining 18 had no evidence of HTR before death. Four Rh- female patients received Rh+ fresh frozen plasma, but none received Rh+ packed red blood cells. Three Rh- male patients received both Rh+ packed red blood cells and fresh frozen plasma, and one received Rh+ fresh frozen plasma. One patient developed anti-Rh D antibodies. None experienced HTR. One female patient had HTR from reactivation of anamnestic JK antibodies. Thirteen (33%) of 39 patients met criteria for HTR based on urinalysis and 29 (40%) of 72 patients tested met criteria for HTR based on hemoglobin and bilirubin values. Only one patient had confirmed HTR. CONCLUSION: High rates of injury recidivism in trauma patients increase the likelihood of multiple blood transfusions during their lifetime. Rh- patients who receive Rh+ blood are at risk of developing anti-Rh antibodies, putting them at risk for HTR. The conservation of Rh- blood for use in female patients may be detrimental to Rh- male patients. Laboratory diagnostic criteria for HTR are nonspecific in the trauma population and should be used with caution.