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Monitoring Laboratory Errors that Cause Patient Harm

Clinical laboratories typically assess their performance based on measures of laboratory efficiency and internal quality rather than patient outcomes. For example CAP recommends 11 quality indicators:

  • Patient/Specimen Identification - percent of patient wristbands with errors, percent of ordered tests with patient ID errors, or percent of results with identification errors
  • Test Order Accuracy - percent of test orders correctly entered into laboratory computer
  • Specimen acceptability - percent of general hematology &/or chemistry accepted for testing. Alternatively, could calculate specimen rejection rate
  • Stat Test TAT - collection to reporting TAT of tests ordered STAT ; can be limited to ED or ICUs; monitor mean or median TAT or percent of specimens with TAT within an established limit
  • Critical Value reporting -percent of critical results with documentation of reporting to caregivers; percent of results for which primary clinician could not be contacted in a reasonable period of time
  • Customer satisfaction - standardized satisfaction survey tool for physicians, nurses & patients
  • Corrected reports for general lab - percent of reports corrected. This could be expressed as correction rate per 10,000 billable tests.
  • Corrected reports for AP - percent of reports corrected
  • Surgical Pathology/ Cytology specimen labeling - percent of requisitions or containers with labeling errors
  • Blood component wastage - percent of components not transfused & wasted
  • Blood culture contamination - percent of cultures contaminated

CAP deems that 8 of these 11 indicators are related to patient safety, but most of them assess only the laboratory’s portion of the total testing process. A recent article by Paul Epner, Janet Gans and Mark Graber states that this narrow approach to process monitoring overlooks important sources of patient harm. They identified five ways that laboratory testing contributes to diagnostic errors in five ways.

  1. An inappropriate test is ordered
  2. An appropriate test is not ordered
  3. An appropriate test result is misapplied
  4. An appropriate test is ordered, but results are delayed
  5. An appropriately ordered test result is inaccurate

When an inappropriate test is ordered, a false positive result can lead to diagnostic error. The clinician may order additional unnecessary tests, procedures or treatments that may cause patient harm. When an appropriate test is not ordered, the clinician may miss key information that is necessary to make a correct diagnosis. Misapplication of test results may be due to misunderstanding of the clinical implications of a result or from unfamiliarity with the limitations of the test method. Another example of misapplication is failure to followup on actionable results. Delays in testing may occur at the preanalytical, analytical or postanalytical stages of the laboratory test cycle. Delays are problematic if a patient’s health deteriorates during the delay or treatment becomes less effective. Finally, the result of an appropriately ordered test may be inaccurate due to variety of reasons including errors in patient identification, specimen collection, analysis or reporting.

The authors have named this strategy the Five Cause Taxonomy for defining appropriate laboratory measures that can reduce the risk of patient harm. They believe this approach gives laboratory professionals an opportunity to greatly expand their mission to benefit clinical providers and patients. Clinical pathologists and laboratory administrators need to find innovative ways to systematically identify and examine testing related-diagnostic error.


Epner PL, et al. When diagnostic testing leads to harm: a new outcomes-based approach for laboratory medicine. BMJ Qual Saf 2013;22:ii6-ii10. doi:10.1136/bmjqs-2012-001621

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