Siemens healthcare diagnostics (siemens) reviewed the data from both bcs xp systems to determine the cause of the discordant, falsely low results with a non-siemens (stago) von willebrand factor antigen (vwf.Ag) reagent and the siemens bc von willebrand reagent.A siemens technical support technician (tst) reviewed calibration curve and quality controls (qcs) on both systems and observed a difference in the running mean in qcs between the systems.A siemens headquarters support center (hsc) specialist further analyzed the event and determined that the issue was sample specific.The hsc specialist determined that the falsely low bias in results was observed for both assays in the first analysis of the sample.The falsely low bias was not observed when the sample was repeated.Based on the operator, both systems were calibrated in (b)(6) and no mechanical or analysis errors were triggered on the affected sample.The operator also indicated that factor viii analysis, conducted using the same sample aliquot, was not affected.The hsc specialist determined that the issue was not system dependent and since qcs recovered within expected ranges at the time of the event, there is no indication of a system issue.The affected sample was a frozen sample and thawing of frozen plasma samples can lead to protein precipitation in the samples.The operator is required to gently mix samples prior to running them to ensure even re-suspension.Inadequate mixing of thawed plasma sample, prior to running the sample, potentially contributed to the discordant, falsely low vwf.Ag and vwf.Ac results.The reagent used to obtain the vwf.Ag results is a non-siemens (stago) reagent and running this assay on the bcs xp system is a user defined method (udm) that has not been validated by siemens.The systems are performing according to specifications.No further evaluation of these systems is required.Mdr 9610806-2018-00011 was filed for the same event.
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Discordant, falsely low von willebrand factor antigen (vwf.Ag) and von willebrand factor ristocetin cofactor activity (vwf.Ac) results were obtained on a patient sample on a bcs xp system using a non-siemens (stago) von willebrand factor antigen (vwf.Ag) reagent and the siemens bc von willebrand reagent.These discordant results were not reported to the physician(s).The same sample was rerun on an alternate bcs xp system, resulting higher.The repeat results were reported to the physician(s) as these results matched the patient's clinical picture and other special coagulation results.The operator indicated that they obtained discordant vwf.Ag and vwf.Ac results on the bcs xp system prior to this event, but did not provide supporting data.There are no known reports of patient intervention or adverse health consequences due to the discordant, falsely low vwf.Ag and vwf.Ac results.
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Siemens healthcare diagnostics (siemens) filed the initial mdr 9610806-2018-00012 on 17-jan-2018.Additional information (06-feb-2018): a siemens headquarters support center (hsc) specialist further analyzed the bcs xp systems back up files and determined that routine system maintenance was performed, as required, on both systems.The hsc specialist reviewed and compared the assay applications and definition for both assays, between the systems, and determined that all settings for siemens assays were acceptable.Based on the error logs, the hsc specialist determined that there was no indication of a malfunction in performance with the bcs xp systems or siemens' bc von willebrand reagent.Quality controls (qcs) for both assays (von willebrand factor antigen (vwf.Ag) and von willebrand factor ristocetin cofactor activity (vwf.Ac)) recovered consistently and typically, within established ranges.Control plasma n recovered out of range multiple times on (b)(6) 2017, but recovered within ranges upon repeat.In the last 6 months, both assays were calibrated multiple times, which is consistent with the typical performance of these products, and the recovery of the calibrations was consistent.Corrected information (07-feb-2018): the "date of event" in section date of event, the date in section other relevant tests/lab data, and the "date received by manufacturer" in the initial mdr was 22-dec-2017.The correct date of event and "date received by manufacturer" was (b)(6) 2017.Additional information (22-feb-2018): the hsc specialist followed up with the operator regarding this event and the operator indicated that they have not obtained further discordant results.The hsc specialist discussed general processing of samples with the operator and the operator indicated the lab receives frozen samples.Then, the operator thaws these samples, places them on a rocker, and thoroughly mixes the samples prior to analysis.Generally, the lab tests factor viii, vwf.Ag and vwf.Ac using the same sample aliquot.Additional sample aliquots are only used when inadequate sample volume is available in the primary aliquot and samples are rerun when the operator obtains questionable results.When the sample is repeated on an alternate system, the operator typically transfers the reagents.The operator also rechecks the sample integrity for questionable samples.The operator also indicated that no discordant results have been generated using the factor viii assay.The cause of the discordant, falsely low vwf.Ag and vwf.Ac results is unknown.The systems and reagent are performing according to specifications.No further evaluation of these systems or reagent is required.Mdr 9610806-2018-00011_s1 was filed for the same event.
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