(P-TS-52) Forward Typing Triumphs: Insights from ABO Blood Group Discrepancy Investigations in PatientsThe ABO Reverse Typing (ABORT–Patient) Study

Sunday, October 20, 2024

12:00 PM - 1:00 PM

Presenting Author(s)

CD

Corey W. Dulek, MSTM, MLS(ASCP)

Mayo Clinic
Dakota, Minnesota, United States

Background/Case Studies: ABO grouping for all patients older than 4 months requires both a forward type (FT) and reverse type (RT) with expectations of Landsteiner’s Law being upheld. Discrepancies between FT and RT are uncommon but resolution by investigation is time-consuming with tests that rarely change the final interpretation. ABO discrepancies are often in the RT and explained by underlying conditions or treatments. We aimed to evaluate the impact of performing subsequent ABO reverse typing in patients who had a history of a resulted ABO.

Study

Design/Methods: Retrospective IRB-approved review of electronic and paper patient testing records at 3 medical centers (2 academic, 1 flagship) was performed to identify samples with ABO typing discrepancies (Figure A). A systematic record review included identifying samples with no type determined (NTD) on initial testing, and/or NTD on repeat manual tube testing if NTD by both methods, ABO discrepancy was confirmed. All discrepancy events were further characterized for involving FT, RT, or both. Extended serologic testing to achieve a final ABO interpretation was captured and this interpretation was compared to the historical type to determine concordance. The study data were collected and managed using an electronic data capture tool.

Results/Findings: In total, 21,220 typing events involving 14,004 patients were reviewed. The frequency of ABO discrepancies was 1.1% (240/21,220). There were 103 grouping events where serologic reactions were consistent with patients’ transfusion, clinical or testing history, and no further testing was required. Among ABO discrepancies, 182/240 (76%) had a historic ABO. Of these 182, 24 were due to FT-only, 146 due to RT-only, and 12 had both FT and RT discrepancies. Of the 158 RT problems, 109 had weak or absent expected reactivity, with 10 having clinical conditions known to suppress ABO iso-hemagglutinins. Furthermore, 49 RT events exhibited unexpected additional reactivity stemming from rouleaux (23 events), cold autoantibodies (21 events), or alloantibodies (5 events), including 3 anti-A1 and 2 anti-M. The cause of 13 RT discrepancies were identical to past findings. Conversely, extended serologic testing of 182 samples from 125 patients did not change the historical ABO interpretation.

Conclusions:

The data underscore the robustness of standalone FT in confirming the ABO group in patients with a historical result. RT has a negligible impact on altering final interpretations. Despite a review of over 21,000 typing events, RT did not change the final ABO interpretation, even after evaluation of the ABO discrepancy. This suggests low clinical utility for routine repeat RT. Revisiting standards and regulations is needed to explore alternative strategies for ABO blood group determination to balance clinical value with efficiency, cost, and sustainability.