{"id":3324,"date":"2026-08-28T08:01:54","date_gmt":"2026-08-28T07:01:54","guid":{"rendered":"https:\/\/seamlessbio.de\/?page_id=3324"},"modified":"2026-08-28T08:09:09","modified_gmt":"2026-08-28T07:09:09","slug":"what-is-ivd-quality-control","status":"publish","type":"page","link":"https:\/\/seamlessbio.de\/de\/what-is-ivd-quality-control\/","title":{"rendered":"What is an IVD Quality Control?"},"content":{"rendered":"
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Quick Definition<\/p>\n

What is an IVD Quality Control?:<\/strong> An IVD quality control (QC) is a material with known or assigned analyte values used to monitor the performance of an in vitro diagnostic assay over time. QC materials are measured alongside patient samples to detect systematic errors, drift, and random imprecision \u2014 ensuring that analytical results are reliable before they are reported for clinical decision-making.<\/p>\n<\/div>\n\n

IQC vs EQA \u2014 what is the difference?<\/h2>\n

Internal Quality Control (IQC)<\/strong> is performed within the laboratory, typically at the start of each analytical run and at defined intervals throughout the working day. IQC samples are measured by the same method and operator as patient samples \u2014 the results are compared to established mean and standard deviation values to detect out-of-control situations before patient results are reported. Failure of IQC triggers investigation and corrective action before the run is accepted.<\/p>\n

External Quality Assessment (EQA)<\/strong>, also called Proficiency Testing (PT), involves the laboratory receiving blind samples from an external provider, measuring them by their routine method, and submitting results. The EQA provider compares results across all participating laboratories to assess inter-laboratory performance. EQA identifies systematic biases that IQC cannot detect \u2014 for example, a calibrator offset that consistently shifts results in one direction while maintaining good precision.<\/p>\n\n

Why does commutability matter?<\/h2>\n

A QC material is commutable when it behaves identically to native patient samples across different measurement procedures. Non-commutable QC materials (e.g. reconstituted lyophilised controls with additives or stabilisers) can give correct results on one platform but systematically biased results on another \u2014 not because the platforms are wrong, but because the matrix of the control reacts differently to different reagent formulations. For multi-platform EQA programmes, commutable native human QC materials are the only format that provides a valid comparison across different analyser systems.<\/p>\n\n

IQC acceptance rules \u2014 Westgard<\/h2>\n

Westgard rules are the standard statistical framework for IQC decision-making. The most commonly applied rules:<\/p>\n