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Background and objectives: In recent years, analytical error rates in medical laboratories have decreased significantly. It has been demonstrated that the majority of errors occur outside of the laboratory in the pre-analytical and post-analytical phases. Our study aimed to evaluate the specimen rejections that occur for various reasons in the central clinical laboratory of a teaching hospital.   
Methods: The study included all specimens (emergency and routine) that were sent from different units of the hospital to the central laboratory between January and December 2019.
Results: Based on the results, 3483 (0.27%) out of 1,307,013 specimens were rejected. The rejection rate was highest for specimens from the intensive care unit (0.69%) and lowest for specimens from the outpatient clinic (0.18%). The specimen rejection rate was 0.42% and 0.22% for specimens from the service unit and emergency department, respectively. The rejection rate for specimens from the intensive care unit was significantly higher than that for specimens from the emergency department (p<0.001), outpatient clinic (p<0.001), and service unit (p=0.010). Although the number of specimens from the intensive care unit was lowest, it had the highest rate of specimen rejection. In our study, most analysis requests were from the outpatient clinic. However, the specimen rejection rate was lowest in this unit.
Conclusion: The results indicate that the reasons for specimen rejection may be influenced by the health status of the patient rather than the patient population.