Evaluation of preanalytical error processes in the microbiology laboratory and effect of training on these processes

Purpose: We aimed to calculate preanalytical error rates in the Medical Microbiology Laboratory of our hospital by the six-sigma method and examine the effect of training on error rates by comparing performances of processes before and after training. Materials and methods: All samples evaluated between 2016-2021 were retrospectively examined. Rejected samples, blood culture contamination rate and urine culture contamination rate were evaluated via Laboratory Error Classification System. The staff obtaining laboratory samples were trained by means of live classes during 2017, 2018 and 2019, and with online classes during 2021. Error rates and sigma levels were calculated before and after training. Results: 685591 samples were accepted by our laboratory; 1175 (0.2%) were rejected. The most frequent cause of rejection (53.4%) was hemolysis of sample. The sigma levels showed hemolysis of the sample as the most frequent cause of rejection, with a value of 4.7 (good performance). Among other quality indicators, the rate of urinary culture contamination was 11.4%, and the rate of blood culture contamination was 3.5%. The total sigma level of urine culture contamination was 2.9 (unacceptable performance), and the total blood culture contamination was 3.5 (minimal performance). Error rates had generally decreased after training, while an increase in performance at the sigma level was detected at all three indicators. Conclusion: In order to minimize preanalytical errors in the medical laboratory, the preanalytical process should be regularly surveyed by quality and performance indicators, and continuing education should provide current information.