(P-TS-60) Identification of Clinically Significant Red Cell Antibody After Transfusion with a Positive Insignificant Result

Background/Case Studies: Solid phase panagglutination (SPAN) is characterized by an initial positive 3-cell antibody screen, over 70% positive reactions in the automated solid phase 14-cell panel, and a subsequent negative Polyethylene Glycol-Indirect Antibody Test (PeG-IAT) screen. Patients are resulted as having a Positive Insignificant (POSIS) screen, making them eligible for electronic crossmatches. However, clinically significant red cell antibodies (RCA) may develop after transfusion, leading to additional workups and increased wait times. This study investigates the development of clinically significant RCA in patients with a history of SPAN.

Study

Design/Methods: Automated solid phase red cell adherence assay was used for antibody screening. The wells of the microplates used in this assay are coated with reagent red cells that react with antibodies in patient plasma at the IgG phase of testing, for which reactions are read 0-4+. Data was compiled from patients identified with a SPAN antibody in 2022, including the date of the latest type and screen (TS), transfusion history post-SPAN identification, and new antibody development. The study did not consider shared factors like demographics or diagnosis.

Results/Findings: Over 1,000 patients with positive antibody screens in 2022 were analyzed, and 51 were identified with SPAN. Of these 51 patients, 21 had a subsequent TS performed after initial identification. After the TS, 15/21 of the patients were transfused. Of these patients transfused, 9 created new antibodies with 6 being clinically significant and 3 clinically insignificant.

Conclusions: Solid phase testing is remarkably sensitive to the extent that non-specific reactions commonly occur. While SPAN results do not necessarily indicate an underlying alloantibody, a percentage of patients developed clinically significant RCA after transfusion. SPAN positive patients should be continuously evaluated for the possible formation of a clinically significant RCA because the identification of new alloantibodies causes the potential need for a full crossmatch through IAT. This would result in a longer wait-time for blood products, increasing the turn-around-time between patient testing and product availability. The correlation between the development of a SPAN and an RCA can be further explored by analyzing other contributing factors to antibody formation.