(P-TS-75) RhD Agnosticism: Routine Provision of RhD Unmatched Blood in the Setting of a National Blood Shortage

Background/Case Studies: Disruptions in the US blood supply during the COVID-19 pandemic have been well-documented, and, to date, the national blood supply continues to experience inventory shortages—particularly a lack of availability of RhD-negative (-) units of all ABO types. During the pandemic, in addition to implementing blood management methods described elsewhere, we implemented a policy of supplying blood for emergent and routine transfusion in an RhD unmatched fashion—male patients of any age and female patients above the age of 50 who were RhD (-) were deemed eligible to receive RhD-positive (+) red cell units if they had no history of anti-D. This RhD agnosticism, which is already used widely in trauma resuscitation, was applied to routine transfusion.

Study

Design/Methods: We retrospectively audited the blood bank LIS to identify all RhD (-) patients who had received RhD (+) pRBC or Whole Blood transfusion during the time period the RhD-agnostic policy was put into effect. To determine percentage of RhD alloimmunization among these patients, we limited that set to those who had a repeat antibody screen at least 21 days after the transfusion of RhD positive blood.

Results/Findings: Overall, a total of 617 RhD (-) patients received 1605 units of RhD (+) blood during non-Trauma transfusions. The RhD alloimmunization rate was 21% (41/198 antibody screens). Among 59 RhD (-) Trauma patients who received 321 RhD (+) units, the RhD alloimmunization rate was also 21% (3/14 antibody screens) during the same time period.

Conclusions: Transfusion of RhD (+) red cells to RhD (-) patients receiving routine and emergent non-Trauma transfusion yielded an alloimmunization rate of 21%. This is significantly lower than prior RhD alloimmunization rates reported in trauma (roughly 40%), and higher than RhD alloimmunization from platelets (roughly 5%). It should be noted that RhD (-) females of childbearing age were not eligible to receive routine RhD (+) red cell transfusion to avoid risk of future development of hemolytic disease of the fetus and newborn (HDFN).

Importance of research: Due to the RhD antigen’s immunogenicity and role in HDFN, transfusion services have historically provided RhD (-) red cell products to all RhD (-) patients. In recent years, RhD agnosticism has been widely adopted and safely used for trauma resuscitation. Due to ongoing RhD (-) pRBC shortages, our geographically-isolated, rural health system, applied the RhD agnosticism of trauma transfusion to routine transfusion. We believe this is the first report on the subject.