Customer reports a single non-reproducible discordant patient result on advia centaur total hcg (thcg) reagent lot 029312.The initial thcg result when the sample was initially tested was positive for pregnancy.The result was questioned by the physician and the same sample was repeated and resulted negative for pregnancy.Advia centaur thcg reagent lot 029312 calibration and qc results were acceptable.Service was sent and a total service check was performed, no instrument issues were identified.Advia centaur thcg precision was evaluated post service, 3 negative patient samples and 2 levels of controls in replicates of 5 were run.The advia centaur thcg precision was found to be acceptable.The customer reports that post service the advia centaur thcg assay is performing within specification.Siemens cannot definitively determine the cause of this discrepant result.Contributing factors such as pre-analytical variables cannot be ruled out.Pre-analytic variables can affect the quality of the sample, and deviation from recommended best practices can lead to erroneous results.Quality control was in range and no issues were noted with other patient samples indicating that the instrument and reagents were performing acceptably.Repeat of the same sample yielded expected results.Based on the results of the investigation, return of the patient sample is not warranted.A product issue has not been identified.The instructions for use states in the interpretation of results section: "interpretation of results of this assay should always be interpreted in conjunction with patient's medical history, clinical presentation and other findings." the limitations section states: "all in vitro assays can generate erroneous results, both clinically false positive results (test results suggesting a condition that is absent) and clinically false negative results (test results failing to identify a condition that is present).".
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