Laboratory Results That Should Be Ignored

Dirk M. Elston, MD


October 11, 2006

Spurious Results Related to Breakdowns in the Testing Cycle

The testing cycle extends from the decision to perform the test through the final interpretation and response to the laboratory result (Figure 1). For decades, quality programs in laboratories have focused almost exclusively on the analytic phase of the testing cycle. Quality efforts that focus on the precision and accuracy of laboratory assays are important, but errors are more likely to arise in the preanalytic and postanalytic phases of testing.[1,2,3,4] Significant gains in quality can be achieved by focusing on these pre- and postanalytic phases.[5,6,7,8,9]

Figure 1.

The testing cycle.

Common sources of error in the preanalytic phase include unintelligible requests, inadequate samples, errors in patient identification and data entry, and errors during collection, transport, and accessioning of specimens. In the postanalytic phase, common errors fall into 3 major categories: (1) turnaround time (result reported too late), (2) routing (report not received by the correct clinician), and misinterpretation (correct result reported, but wrong clinical action taken).[10] Because these types of error involve both the laboratory and clinician, both must be involved in efforts to reduce errors.

Figure 2 demonstrates the portion of the testing cycle that has been traditionally addressed by laboratory quality programs. Figure 3 gives a sense of the opportunity for gains in quality if the entire testing cycle is addressed. Errors in the pre- and postanalytic phases may be attributable to the clinician, the laboratory, or the system. An effective quality program relies on active participation from all participants in the testing process. Data entry errors remain a major cause of spurious laboratory results. Every requirement for manual data entry or transfer creates an opportunity for error. A specimen may be labeled at the bedside, with the same critical information entered as a separate process on the request form and again in the laboratory data system. Failure mode analysis of the processes involved often identifies separate requirements for manual entry of 15 or more digits for the test, 5 digits for the operator, and an additional 12 for patient billing information. Bar coding at the point of care can reduce medical errors related to data entry.[11,12] Even when bar coding is instituted, scanning errors may be related to multiple wristbands and incorrect codes related to hospital transfer or previous hospitalizations. Verification of the scanned information is still required. Manual data entry may still be required when bar-coded scans are unsuccessful. Information technology systems must ensure the integration of communication throughout the testing cycle. Common standards are required for data reporting systems to ensure that they communicate with each other with seamless electronic transfer of data and the ability to capture asynchronous data. Clinical decision support can be integrated into these systems to enhance effective communication.[13] Errors in communication can also be reduced through the use of bar-coded phrase sheets and keyboard macros.[14]

Figure 2.

Quality efforts have traditionally focused only on the analytic phase.

Figure 3.

The opportunity for improvement.


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