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The customer reported false positive test results with anti-a when donor samples were tested as a negative with the reagent of a competitor.The customer used a 4% suspension of unwashed segments and performed the method immediate spin.The customer did not provide a date of event.The customer returned the supposedly defective product and one donor sample that had caused false positive reactions.The donor sample was provided as three segments (pigtails) labeled as (b)(6).Ohr quality control laboratory tested the donor sample with the supposedly defective product in the method immediate spin according the instruction for use and yielded a weak positive reaction.Additionally the complaint sample was tested for potency and specificity.All acceptance criteria were met.The minimum titer of 64 was exceeded.Because the segments did not contain any serum or plasma reverse typing and testing for irregular red cell antibodies was not possible.Therefore the possible influence of an antibody can not be excluded.Due to the fact that segments (pigtails) are not suited for the molecular typing the segments could not be sent to an external laboratory for molecular abo typing.The weak positive reaction of the donor sample might be explained by the note in the chapter "specific performance characteristics" of the instruction for use: "seraclone anti-a has the ability to detect minute quantities of a-antigens on red cells (e.G.Ax).However, this capability allows clinical insignificants numbers of a antigens to be detected as in rare cases of b individuals with elevated a antigen level (e.G.B(a) phenomena.Testing by our quality control laboratory confirmed the allegedly defective lot of seraclone anti-a functions correctly.A review of the batch record documentation showed no irregularities which might have negatively affected the quality of the allegedly defective lot.Based on the test results with this particular donor sample the complaint is classified as confirmed - expected product performance epp.The phenomenon escalated by the customer has been confirmed, but it is not due to any defect in the product and the instruction for use contained a corresponding hint, therefore, no further actions were necessary.
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