This report is being filed to provide additional information and investigation: blood bags with the leukoreduction filter was returned for evaluation.The leukoreduction filter was tested for flow rate and air leaks.A swift flow rate of 37.5 ml/min was noted and it was confirmed there were no air leaks.The manufacturing records, test records, and inspection records were reviewed for abnormalities and none were found.The records regarding the particulate removal rates of the filter membranes were reviewed.All membranes conformed to established specification.Root cause: a definitive root cause for the observed elevated wbc count remains undetermined at this time.Based on the available information, it cannot be ruled out that the higher-than-expected wbc content in the whole blood product could be donor-related(characteristics of blood).It also cannot be ruled out that a filtering error or other process error(not resting the collected blood prior to filtering; not expressing air properly from the product bag) could have contributed to the higher-than-expected wbc content in the whole blood product.The instructions for use provide a caution to not squeeze or apply pressure to the filter while it is attached to the bag containing the filtered blood and to clamp the blood filled tubing before the blood enters the filter in order to avoid leukocyte leakage.
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