[Quality of the performance of clinical laboratories].

The quality performance of clinical laboratories plays a basic role in the quality and effectiveness of health care. The reliability of laboratory tests, however, depends on the quality assurance system existing in the working place, which comprises not only the analytical activities but includes all preventive measures and their regular control in connection with the preanalytical phase, as well as the plausibility control and interpretation of results. The external quality assessment of laboratory work gives information about the systematic errors existing between results of different laboratories, and it helps to discover rough errors of either random or systematic origin. The external quality assessment of medical laboratories has its beginning in early 1970's in Hungary and since 1975 it is organized continuously by the National Institute. In recent years, the external quality assessment of laboratories is performed in cooperation and support of the INSTAND e.V./WHO Collaborating Center (Düsseldorf). The paper surveys the quality performance of laboratories in routine clinical chemistry, haematology, blood-coagulation, hormone and blood-gas analysis. Moreover, the evaluation of results on the basis of reference and assigned values measured in the reference laboratories and according to the statistical error of results of participants is also discussed. Further improvement in the quality performance of health laboratory service needs the introduction of unified quality system which includes details of all elements of knowledges and technical activities necessary to fulfill requirement of reliable and effective laboratory work.