Clinical laboratory results are inherently uncertain. Variability arises when repeating
measurements of the same sample under different conditions. Measurement uncertainty
(MU) is a metrological framework that quantifies this variability, enabling clinical
interpretation and comparison of results within and between patients. In haemostasis
assays, MU describes uncertainty propagation across the entire traceability chain—from
international standards to final patient results.
The Guide to the Expression of Uncertainty of Measurement (GUM)1 offered a statistically
rigorous but complex method for estimating MU, limiting its widespread adoption. A
relatively recent technical specification (TS) from the International Standardisation
Organisation (ISO) (ISO/TS 20914:2019)2 introduced a Top-down approach that balances
rigour with operational feasibility, supporting ISO 151893 compliance. However, its
applicability to specialist areas such as haemostasis has been questioned. Furthermore,
despite improved understanding of calculation methods, international guidance recommends
against reporting results, together with MU, directly to service users, instead the
laboratory is required to provide it upon request. This review explores the implementation
of different approaches for MU in haemostasis laboratories.
