Pre-analytical phase errors constitute the vast majority of errors in clinical laboratory testing

Objectives: Clinical laboratory errors pose a threat to patient safety and previous studies have demonstrated that pre-analytical error is the most common error type. Our study aimed to determine the types and frequency of errors occurring in clinical laboratory testing in contemporary practice. Methods: Errors occurring in a core laboratory between 01/2022 and 05/2023 were recorded retrospectively. Errors were quantified using multiple data-streams including real-time manual technologist intervention, incidence reports filed by hospital staff/physicians, and retrospective assessment using automated reports from the lab information system (LIS). Errors were adjudicated and binned into pre-analytical, analytical, and post-analytical phases. Total test volumes were assessed in the LIS and electronic medical record. Results: There were 37,680,242 billable results reported from approximately 11,000,000 specimens during the study period. In total, 87,317 errors occurred impacting 0.23% (2,300ppm) of billable results and approximately 0.79% (7,900ppm) of specimens. Among these errors, 85,894 (98.4%, 984,000ppm) were in the pre-analytical, 451 (0.5%, 5,000ppm) were in the analytical, and 972 (1.1%, 11,000ppm) occurred in the post-analytical phase. Hemolysis impacting specimen integrity (60,748/87,317, 69.6%, 696,000ppm) was the most common error. When excluding hemolysis, there were 26,569 errors documented (0.06%, 600ppm of billable results), among which 94.6%, 1.7% (17,000ppm) and 3.7% (37,000ppm) were in the pre-analytical, analytical and post-analytical phase respectively. Conclusions: Observed error rates were consistent with previous studies with pre-analytical errors comprising most errors. High prevalence of pre-analytical errors implies a need for enhanced tools for error detection and mitigation in the pre-analytical phase of testing.