Among trauma patients of child-bearing potential who undergo transfusion with RhD-positive red blood cells (RBCs), the rate of RhD-alloimmunization may be greater than 40%, according to research published in Hematology.

Previous research suggests that trauma patients undergoing resuscitation who receive early transfusion using an RBC and plasma combination have improved survival. These findings may lead emergency services and hospital systems to provide transfusions to help reduce the risk of mortality.

In these situations, however, it is unlikely that patient blood type will be known at the time of transfusion. Where patients are RhD-negative or RhD-unknown and are of child-bearing potential – often defined as between 13 and 50 years old – RhD-negative RBCs or low titer group O whole blood (LTOWB) is preferred, because RhD-alloimmunization may affect future pregnancies.

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As RhD-negative RBCs and LTOWB are not commonly stored in emergency service settings, RhD-positive RBCs and LTOWB may be used in an emergency, regardless of patient characteristics. Because of the potential impact this may have on pregnancies, understanding the overall RhD- alloimmunization rate when RhD-positive RBCs with or without LTOWB are used may help to predict the risk of complication.

For this review-based study, researchers analyzed “the RhD-alloimmunization rate in injured patients who were between 13 and 50 years old so as to be able to understand the risk involved with transfusing [females of reproductive potential] of unknown or negative RhD-type with RhD-positive RBCs or LTOWB during their trauma resuscitation vis-à-vis future [hemolytic disease of the fetus and newborn] risk.”

Over the 20-year period evaluated, 96 patients were identified and included in this analysis. All patients were RhD-negative and were treated at an American Level 1 trauma center for injury, and were provided at least 1 unit of RBCs or LTOWB during resuscitation. The median patient age was 33 years and 90 (93.8%) were male; 74% (71) also had an injury severity score of greater than 15.

The analysis suggested that 42.7% (41 of 91; 95% CI: 32.7-53.2) of the patients evaluated were RhD-alloimmunized post-transfusion with a median of 3 units of RhD-positive RBCs with or without LTOWB.

The authors suggested, further, that while these findings were in a predominately male-patient group, they are likely to generalize to the female population.


Yazer M, Triulzi D, Sperry J, Corcos A, Seheult J. Rate of RhD-alloimmunization after the transfusion of RhD-positive red blood cell containing products among injured patients of childbearing age: single center experience and narrative literature review. Hematology. 2021;26(1):321-327. doi:10.1080/16078454.2021.1905395