Quality assurance in laboratory haematology

SynopsisQuality assurance in laboratory haematology includes (a) constant checking of test reliability by internal quality control, (b) external quality assessment by an independent agency to check performance of a number of laboratories at intervals in order to obtain a retrospective indication of their ability and (c) proficiency control by supervision of the pre-test and post-test phases of laboratory work, from specimen collection to delivery of the report to the clinician.The procedures which comprise quality control are described; these include use of control preparations with control charts, CUSUM analysis, constancy of daily means of the blood count indices of ‘absolute values’, duplicate testing, clinical correlation and the important role of the blood film to check the instrument-derived blood count measurements.A description of the functions of an external quality assessment scheme is based on the UK National Scheme (UK NEQAS). The blood count and other tests of general haematology have been used as models to describe the procedures for qualitative and quantitative tests, low results are analysed and performance is assessed. The tribulations and triumphs of NEQAS are described and it is concluded that NEQAS has a vital role in ensuring good laboratory practice in general, and the reliability of the individual laboratories who participate in the scheme. NEQAS, in turn, must ensure its own ability to provide stable materials which are suitable for each test in the programme, and to analyse data correctly. There is also need to take account of the continued expansion of laboratory services as new techniques are introduced and to develop appropriate EQA procedures and materials in order to incorporate these in a comprehensive scheme.