Abstract
Accreditation is a valuable resource for clinical laboratories and the development of an International Standard for their accreditation represented a milestone on the path towards improved quality and safety in laboratory medicine. The recent revision of the International Standard, ISO 15189, has further strengthened its value not only for improving the quality system of a clinical laboratory but also for better answering the request for competence, focus on customers' needs and ultimate value of laboratory services. Although in some countries more general standards such as ISO 9001 for quality systems or ISO 17025 for testing laboratories are still used, there is increasing recognition of the value of ISO 15189 as the most appropriate and useful standard for the accreditation of medical laboratories. In fact, only this International Standard recognizes the importance of all steps of the total testing process, namely extra-analytical phases, the need to focus on technical competence in addition to quality systems, and the focus on customers' needs. However, the number of accredited laboratories largely varies between European countries and also major differences affect the approaches to accreditation promoted by the national bodies. In particular, some national accreditation bodies perpetuate the use of fixed scopes, while the European co-operation for accreditation (EA) and the European Federation of Laboratory Medicine (EFLM) Working Group promote the use of flexible scopes. Major issues in clinical laboratory accreditation are the verification of examination procedures for imprecision, trueness and diagnostic accuracy and for estimating measurement uncertainty. In addition, quality indicators (QIs) are a fundamental requirement of the ISO 15189 International Standard.