(P-TS-73) Retrospective Review of Unexpected Red Cell Antibody Development After Transfusion of Non-Identical Rh Type Red Blood Cells

Background/Case Studies: The national blood shortage has impacted the manner in which blood centers and transfusion services manage inventory. A large blood center (BC) operates multiple transfusion services (TS) inside a number of level I and level II trauma centers. Routine emergency release practices for males and women of non-childbearing age include the transfusion of uncrossmatched Group O RhD-positive red cells (RBC) when time does not allow for pre-transfusion testing to be performed. In rare, high-usage situations the transfusion of RhD-negative woman of childbearing age with RhD-positive RBCs may also occur.

Study

Design/Methods: The TS evaluated the records of 140 RhD-negative recipients who received RhD-positive RBCs or Low Titer Group O RhD-positive Whole Blood (LTOWB) between January 1- December 31, 2022. The records of these recipients were reviewed to determine if the development of unexpected antibodies occurred. Only anti-D and other Rh antibodies were noted in this study.

Results/Findings: During the study period, 577 units of RhD-positive RBC / LTOWB were transfused to 140 patients: 96 (69%) males and 44 (31%) females. Follow-up testing on 55 patients was not available, and it is unknown if antibodies developed. Of the 85 RhD-negative patients transfused RhD-positive RBCs with complete records, 20 (24%) patients developed clinically significant red cell alloantibodies directed against Rh antigens. and 19 developed an anti-D. (Table 1)
Two (4.5%) of the RhD- negative females transfused RhD-positive RBC/LTOWB, were of childbearing potential and both developed clinically significant RhD- antibodies: A 47-year-old was transfused 1 RhD-positive unit, and anti-D was identified 5 months post-transfusion. A 39-year-old was transfused 6 units (4 RBC and 2 LTOWB), and anti-D,-C, -E were identified 2 months post-transfusion.

Conclusions: When inventory levels of RhD-negative RBCs are unable to meet demand, the clinician must evaluate if the potential consequences of transfusion of RhD-positive RBC outweigh the risk of delaying the transfusion. This retrospective study evaluated the likelihood of one of the negative consequences: the development of clinically significant Rh antibodies. The results of this study provide additional information to the clinician to assist with making a determination if it may be worth the risk to transfuse RhD-positive RBC to RhD-negative patients rather than delay transfusion.

Importance of research: Monitoring of transfusion practices is a vital element of Transfusion Medicine in order to improve blood management and patient care. The results of this study provide additional information to the clinician to assist with making the determination if transfusion of RhD-positive RBC to RhD-negative patients rather than delay transfusion is an acceptable risk.