[Quality control in coprology]

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.