External quality assurance programmes in medical laboratories

Medical laboratories have a long tradition of external quality assessment. Starting from pure quality control of laboratory performances, most schemes have evolved to a powerful tool for improving quality of clinical outcome of results. External quality assurance in medical laboratories not only inc ludes laboratory performance evaluation, but also evaluation of method perf ormance, postmarked vigilance, training and help. In the future, the qualit y of programmes must further be improved by accreditation of schemes and by using electronic data interchange.