The customer reported elevated white blood cell (wbc) content in a filtered whole blood unit.There was not a transfusion recipient or patient involved at the time of whole blood processing,therefore, no patient information is reasonably known at the time of the event.Donor unit #: (b)(4) the whole blood collection set is not available for return because it was discarded by the customer.
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Investigation: the whole blood collection set was not returned to terumo bct forevaluation.The manufacturing records, test records, and inspection records were reviewed forabnormalities and none were found.The records regarding the particulate removal rates of the filter membranes were reviewed.Allmembranes conformed to established specification.Shipping testing was performed on the reserve samples from the reported lot number.Thereserve samples were also visually examined and the solution volume and solution compositionwere tested with no abnormalities noted.All product conformed to the establishedspecification.Root cause: a definitive root cause for the observed elevated wbc count remainsundetermined at this time.Based on the available information, it cannot be ruled out that thehigher-than-expected wbc content in the whole blood product could be due to an occlusion,blood may have been filtered by a smaller than usual filter area.As a result, linear speed mayhave increased and leukocyte leakage may have occurred.As an increase of wbccontamination complaints were noted from previous lot number, further investigation wasperformed.Investigation results indicated that the cause of higher-than-expected wbccontent in the whole blood product was due to the maximum pore size of the filter membraneis likely to increase according to the combination of multiple parameters in manufacture ofleukoreduction filter membranes and wbc contamination is likely to occur frequently in theproduct lots of which the maximum pore size of the filter membrane has increased.Theinstructions for use provide a caution to not squeeze or apply pressure to the filter while it isattached to the bag containing the filtered blood and also to clamp the blood filled tubingbefore blood enters the filter in order to avoid leukocyte leakage.Corrective action: an internal capa has been initiated to review the maximum pore size ofthe filter membrane and the likelihood of an increase according to the combination of themultiple parameters.In addition, the wbc contamination is likely to occur frequently in theproduct lots of which the maximum pore size of the filter membrane has increased.To achievea resolution, manufacturing specifications were updated to narrow the range of the parametersin the manufacture of filter membranes and it was confirmed that the appropriate level of themaximum pore size of the filter membrane was achieved.
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