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The user indicated getting a false positive with the anti-d well whereas they had typed the patient as b rhd negative.Investigation: - data review: the rhd negative result was confirmed after several repeats in the same work conditions, and also in manual with tube technique.- trend analysis : on the (b)(6)., 6 complaints on the ih-card abo/d(dvi-)+rev a1b pn 813112100 product reference.But this case in the unique record on the lot 9546010.- batch records : the manufacturing quality records for the reported products are all in compliance and that all specifications were met at batch release.- traces files analysis : several potential explanations were considered, including (dried gel in the anti-dvi- well, fibrin in the rbc dilution, carryover between the wells, or inter-sample carryover from the prior sample "(b)(6)," which is of o blood type and contains high titers of anti-a and anti-b antibodies).Unfortunately, none of these hypotheses have proven to be demonstrable or valid, due to the unavailability of the gel control image, and primarily because the dispensing sequence went from the ctl well to the anti-a well, passing through the anti-dvi- and anti-b wells.And we can see the ctl well is negative.The findings do not allow us to determine the root cause of this false positive reaction at the moment.We can conclude on a punctual phenomenon, likely caused by a microparticle, fibrin strand, or particulate contamination introduced during sample dispensing.Gel techniques are known to occasionally produce anomalous reactions when erythrocytes become trapped by fibrin strands or particulate material within the gel matrix.Human monoclonal igm anti-d reagents may amplify non-specific erythrocyte bridging when such artefacts are present, explaining the isolated reaction.Cold antibodies or non-specific cold agglutination can be ruled out, as these would typically affect all wells containing red blood cells, including the control, and would be reproducible on repeat testing.
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