Systematic Bias in Hematology What the SDI Trend Shows

A useful hematology quality case in the context of ISO 15189. This image, originally shared publicly by another professional on LinkedIn, is a good example of why quality interpretation should go beyond a simple pass/fail view of QC. The screenshot shows an SDI trend for MCV across three control levels in a peer-group monitoring platform. What stands out is the initial persistent negative shift across all three levels, followed later by a return toward the peer-group mean. That pattern is consistent with systematic bias, not just random variation. It also highlights an important practical point: a reassuring routine QC impression does not always exclude a meaningful analytical shift. This is where peer-group comparison, trend review, and documented effectiveness checks become especially valuable under ISO 15189. In a case like this, the quality discussion should include: interpretation of the trend, not just isolated points evaluation of possible calibration-related bias appropriate correction and verification that the action actually restored alignment This is the difference between routine QC review and real quality management. Credit: the image discussed here was originally shared publicly on LinkedIn by another professional and is referenced for educational commentary. Hashtags #ISO15189 #Hematology #QualityControl #InternalQC #SDI #Bias #CAPA #PeerGroup #LaboratoryQuality #ClinicalLaboratory #MedicalLaboratory #Calibration #QualityManagement #LaboratoryMedicine