(P-TS-70) Mixed Field Results with Automated Instruments

ABO typing is a test that no technologist wants to get wrong due to the potential for a life-threatening sentinel event, should an incorrect unit of blood be administered. Those patients who have been transfused with a different blood type, had a bone marrow transplant with a new donor blood type, or for other reasons where a blood sample may have dual populations of cells, patient types (ABO/Rh) may not always be straightforward. These samples may present with mixed field reactions. With a shortage of tenured staff and more generalists performing testing, it is imperative to have proper training, competency, and sound testing algorithms. Regardless of method, mixed field reactions are important to recognize and resolve.  The purpose of this study is to review the presentation of mixed field on the Echo Lumena (Werfen, Norcross, GA), as compared to tube methodology.

Study

Design/Methods:

We reviewed workups from 2023 at our facility, specifically looking for mixed-field results requiring additional work-up by the staff. We compared how these cases would be worked up if presented in tube vs. on the instrument to determine if there was advantage over one vs. the other.

Results/Findings: Regardless of testing method, the historical check alerted the performing tech to the possibility of mixed field. The next step involved was reviewing the results and comparing them with past records. This stage remained consistent for both tube and automated assessments.  In both tube and Echo methods, the results prompted further investigation (see Table 1). Whenever the Echo system labeled a reaction as equivocal (?), the visual inspection consistently showed a notable clumping of cells against a hazy background of unagglutinated cells indicating that the camera was able to identify smaller agglutinates in the background caused by the mixed field population and allow the software's algorithm to flag the result.

Conclusions:

Our test volume necessitates use of automation. While this study only encompasses a small subset of patients, it illustrates comparable results on the instrument to those observed in manual hemagglutination testing. An advantage of our automation is the utilization of identical reagents for bench testing as those employed on the instrument, aiding in eliminating variables when comparing results across different methods. Despite variations in the strength of reactions between automated and manual results, the overall interpretation and approach to the workup remained consistent. We understand that no instrumentation can fully address the complexities of challenging patient types, but we appreciate the standardized shaking over the potential variation seen in manual procedures. The instrument successfully alerted the user to the mixed field results so appropriate action could be taken.