2024-07-052024-07-052020-02-010250-4685https://doi.org/10.1515/tjb-2018-0119https://hdl.handle.net/11452/42945Background: It is responsibility of medical laboratories to determine and reject nonconforming samples as well as take preventive actions. In this study, we examined reasons and percentages of rejected samples. We also investigated impact of the preventive actions on decreasing the rejection rates.Materials and methods: Reasons for rejection were determined by Pareto analysis. Sigma analysis was used for each month to evaluate the ratios and compare with other studies. Some preventive actions were taken to reduce the rejection rates. Pearson's chi square test was used to evaluate effects of preventive actions. Significance level was determined as p <0.05.Results: Most of the rejected samples consisted of samples not received by the laboratory, haemolysed and insufficient samples. The percentages of samples not received by the laboratory and insufficient samples were reduced from 3.80% to 1.94% and 0.33% to 0.31% respectively, while haemolysed samples percentage was increased from 2.83% to 3.37% after the improvement actions. Also, sigma levels for samples not received by the laboratory and haemolysed samples were at the minimum while insufficient samples were at a reasonable level.Conclusion: Improvement actions achieved statistically significant decreases for samples not received by the laboratories for a long-term.eninfo:eu-repo/semantics/closedAccessQuality indicatorsErrorsSigma levelPre-analytical errorRejection ratesScience & technologyLife sciences & biomedicineBiochemistry & molecular biologyArticle000525736100003192545110.1515/tjb-2018-0119