[Pre-analytical quality assessment in the microbiology laboratory].

Background: Errors in the pre-analytical phase of the microbiology laboratory reduce patient safety and generate additional expenses. In Mexico we do not have systems for evaluation and monitoring of the pre-analytical phase; quality indicators are proposed for continuous improvement. Objective: Identify the main reasons for rejection of respiratory samples in the microbiology laboratory and evaluate the usefulness of preanalytical quality indicators. Material and methods: Cross-sectional study. Review of microbiology laboratory applications from August 2022 to July 2023, calculated the frequency of rejection and identification of the main reasons for it, it was analyzed using quality indicators based on the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). Results: Of 3530 processing requests, 582 were for respiratory samples (16.48%), 44 samples rejected due to pre-analytical errors (7.56%), the main causes identified: Transcription error 22.7%, identification error 20.4%, Samples that do not comply Murray-Washington criteria 25.0%, Errors in obtaining/collecting samples 20.4%, Samples with defects in conservation 4.5%, Unidentified samples: 6.8. Conclusions: The main causes of rejection were identified; upon analysis with the preanalytical quality indicators, they were found at desirable levels and in reference ranges; only 4 were useful for long-term implementation.