Background: Urinary sediment components are mainly unstable, especially in their original forms. This makes the use of such material in routine external quality assessment surveys (EQAS) almost impossible. The development of an alternative EQAS for urinary sediment using photomicrographs (visual-sample EQAS) is described here, together with results, improvements and future plans.
Methods: The original survey allowed a free-text interpretation, which proved to be time consuming and impractical. The next phase included a multiple choice answer (one from five alternatives). The current version challenges the participant with a list of over 50 alternatives, together with a “not-in-the-list” possibility.
Results: Certain elements are always interpreted more correctly (examples: erythrocytes, squamous cells, renal epithelial cells, bacteria - above 90%) than others (examples: leukocytes, fat droplets, certain crystals - below 55%). Pictures are included which are atypical (for example: decoy cells, which must be interpreted correctly, other artefacts). Occasionally interesting structures are included, but which are not evaluated.
Conclusions: The two-dimensional pictures often limited the interpretation possibilities, so that in such cases more than one answer was allowed. The possibility of “online microscopy” using staple pictures is at present in evaluation. The acceptance of this type of EQAS is seen by the number of participants, at present over 500 per survey, four surveys per year.