Résumé
Since 1994, quality in medical biology laboratories has been defined by decree in the Guide to Good Execution of Analyzes (GBEA). The constraints specific to coprology make it difficult to apply certain points of the GBEA. In particular, no quality control is available in this area. However, the fecal matrix is complex, heterogeneous and variable depending on the pathologies, surgical interventions, diet and therapy. The commercial serum quality controls do not make it possible to highlight the analytical interferences linked to a matrix effect. This led us to develop our own quality control using a mixture of lyophilized patient stools to improve the quality assurance of the analytical phase. The techniques used in coprology are manual or semi-automated and involve a pre-analytical phase which is not always taken into account by quality controls. A semi-quantitative approach by microscopic analysis of the stool is therefore coupled with the assay. This constitutes an internal control for each sample. The quality approach is continued at the post-analytical level: the analyzes are compared with each other and put back into the clinical and therapeutic context of the patient. The implementation of all the tools described above ensures the reliability of the results provided and allows the long-term follow-up of a patient.
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Summary
Quality control in medical laboratories was defined in guidelines for good execution of laboratory analyses issued by the French health authorities in 1994. Application of these guidelines is difficult in coprology because the sample is a complex heterogeneous matrix which varies with disease, surgery, food intake, and treatment. In addition, commercial quality control kits are not available for stool biochemical analyses and a national quality control program has not been established. We thus developed our own fecal quality control technique using pooling lyophylized stool samples. Manual or partially automated methods are used in coprology, leading to a long pre-analysis phase which is not always taken into account in quality control. This implies the need for complementary tools to insure the quality of coprology analyses. For example, semi-quantitative microscopic lipid analysis can be used as an internal standard for a given specimen. Quality assurance also involves a post-analytical phase where results obtained for a given specimen are compared with other available data and interpreted in light of the patient‘s clinical and therapeutic status. This quality assurance strategy enables accurate reliable results useful for long-term patient management.
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Keywords
Coprologie
Quality assurance
GBEA
Quality control
Faecal lipids
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Key-words
Coprology
Quality control
Quality assurance
Fecal lipids
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Copyright © 2004 Elsevier Masson SAS. All rights reserved.
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