Siemens has completed the investigation: the cause of the hematocrit (hct) discrepancy could not be determined from the information provided by the customer.A review of the in-house performance (including retain testing) for the card lot used, 10-20216-20, did not identify any product deficiencies.The failure rate of lot 10-20216-20 is not showing an increased trend in the field, therefore, there is no further evidence that the system or reagent cards are not performing as intended.The csv files provided by the customer offered additional insights and brought value to the investigation.From the information provided by the customer, there are a few factors that may have contributed to a discrepant hct reading.Firstly, different sample draws (collection site, collection method, time delays), sample handling and testing delays are known to affect test results if proper precautions are not considered.On 12 nov 2020, it was indicated that the epoc sample was tested at 5:41 am, resulting in an iqc failure (sample delivery failure).The same sample was then tested again at 5:47 am on epoc (6 min delay), providing the hct result of 27 %pcv.It should be noted that delays in testing a drawn blood sample in the absence of anticoagulant increase the risk associated with clotting and mixing (sample handling) related issues - which in turn can lead to discrepant readings.Secondly, the methods of hct measurement are not the same with epoc and the comparative instrument.Sysmex uses a complete blood cell count (cbc) method, which has known limitations associated with the calculation of falsely elevated values when a high reticulocyte or white blood cell (wbc) count is present.This is because the higher cell volumes of wbcs/ reticulocytes can interfere with the rbc count and thus falsely increase the hct reading.The customer has confirmed the patient's reticulocyte count was slightly elevated and wbc count was high, therefore, the impact/contribution of this measurement method cannot be ruled out as a potential elevated result on the sysmex.Thirdly, it was indicated by the customer that the sysmex xn 3000 utilized a sample with k2 edta anticoagulant.It is well documented in literature that the mean cell volumes of k3 edta anticoagulated blood are approximately 4% less than k2 edta anticoagulated blood.While the choice of anticoagulant affects the microhematocrit method to which all hematocrit methods are calibrated, results from routine samples on hematology analyzers are independent of the anticoagulant used.Since most clinical hematology analyzers are calibrated by the microhematocrit method using k3 edta anticoagulant, the epoc system is calibrated to a k3 edta microhematocrit method.If the sysmex instrument is calibrated to k2 edta anticoagulated blood, it will read ~4% higher than epoc.In these situations epoc advises a correction factor of 1.045 (e.G.K2 edta sysmex / 1.045).
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