Aim: In this study, it was aimed to evaluate the preanalytical process performance in our laboratory with the six-sigma methodology and to investigate the effect of the training given to the hospital staff on the sigma values.

Materials and Methods: Acceptance and rejection data of the thirteen-month period (between 2020- 2021 March), biochemistry, hormone, hemogram, blood gas, HbA1c, coagulation and urine samples were retrospectively analyzed through the hospital information system. Inappropriate rejected samples were classified according to the reasons for rejection.

Results: In our study, the total number of samples was found to be 372876, the total number of rejected samples was 2673, and also sigma level was calculated as 4 for the study period. The sigma level was calculated as 4.0 for the pre-training ten-month period and 4.1 for the post-training threemonth period. According to the Pareto analysis, the first three causes of rejection were clots, hemolysis, and insufficient samples, respectively. Compared to the pre-training period, there was a significant decrease in the number and percentage of rejection due to insufficient sample (respectively p<0.05, p<0.01) and a significant increase in the sigma value in the post-training period (p<0.01). The change in other reasons for rejection was not statistically significant (p>0.05).

Conclusion: Our study includes data from the first period of the Covid-19 pandemic in our country and after. During this period, there was a decrease in the total number of samples. Due to the high staff mobility in this period, enough staff could not be trained. This is an another reason why factors other than the reason for rejection due to insufficient sample do not reach the desired level.