Preanalytical Phase Errors: Experience of a Central Laboratory

Preanalytical errors contribute significantly to diagnostic inaccuracies, yet their frequency and sources remain understudied. Prior research has shown that these errors often occur outside the laboratory, particularly during specimen collection. However, the exact proportions and types of errors remain unclear. This gap motivated a focused study on preanalytical errors, using quality indicators to assess their occurrence. The study aimed to distinguish between errors within and outside the clinical laboratory. No prior work had resolved how many errors happen during blood collection versus during sample handling. The lack of detailed data on specific error types, such as incorrect fill volumes or clotted samples, limits quality improvement efforts. By examining nurses' practices and comparing them to laboratory data, the study sought to clarify these uncertainties. This approach allows for targeted interventions to reduce diagnostic errors and improve patient outcomes.

The study aimed to evaluate the frequency of preanalytical phase errors both inside and outside the clinical laboratory. It focused on identifying specific types of errors and their sources to inform quality improvement strategies. The researchers observed blood collection practices and sample handling to determine where errors most commonly occur. They used quality indicators to assess the data systematically. The study's goal was to compare observational findings with laboratory information system data. This comparison would highlight discrepancies and reveal patterns in error occurrence. By analyzing both short-term and long-term data, the study aimed to provide a comprehensive view of preanalytical errors. The findings could help prioritize interventions to reduce diagnostic inaccuracies and improve laboratory processes.

The study involved a one-week observational period focusing on 73 nurses drawing blood from 337 patients. Two stages were analyzed: blood collection up to sample receipt and sample handling up to the analytical phase. Data on patient numbers, tests, and rejection rates were extracted from the laboratory information system for both one-week and one-year periods. Observations were conducted in real-time to capture errors during specimen collection. The researchers counted the number of tubes used and categorized errors based on predefined quality indicators. Biochemistry tubes were evaluated for fill volume, hemolysis, clotting, and fibrin presence. Safety mechanisms of needles were assessed for proper activation. The data were compared to identify trends and discrepancies between observational and system-based findings.

The study found that 38% of safety needles had properly activated mechanisms, despite 78% of nurses using them. Incorrect fill volume was observed in 40% of biochemistry tubes. Hemolysis occurred in 17% of these tubes, while clotted samples and fibrin were seen in 6%. EDTA tubes had a 12% incorrect fill volume error, and citrated tubes had a 20% error rate. Clotted samples and platelet clumps were found in 1% of EDTA tubes. These results highlight significant issues in sample collection and handling. The data from the laboratory information system corroborated the observational findings. The comparison revealed consistent patterns in preanalytical errors across both short-term and long-term periods.

The study confirms that preanalytical phase errors occur frequently both inside and outside the clinical laboratory. The researchers found that errors such as incorrect fill volume and hemolysis are common during specimen collection. These findings suggest that quality indicators can effectively track and categorize such errors. The data from the laboratory information system supported the observational results. The study does not propose new interventions but emphasizes the need for targeted improvements. It suggests that addressing safety needle activation and fill volume accuracy could reduce diagnostic errors. The results highlight the importance of monitoring and training healthcare staff involved in specimen collection. The authors do not claim that these errors are the sole cause of diagnostic inaccuracies but stress their significant contribution.