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David Plaut: Off the Cuff

Laboratory Errors

Published August 22, 2014 12:54 PM by David Plaut

Laboratories have a major impact on patient safety: 80-90% of all the diagnoses are made on the basis of laboratory tests. Laboratory errors have a reported frequency of 0.012-0.6% of all test results.

Patient safety is a managerial issue which can be enhanced by implementing active system to identify and monitor quality failures. This can be facilitated by reactive method which includes incident reporting followed by root cause analysis. This leads to identification and correction of weaknesses in policies and procedures in the system. Another way is a proactive method like Failure Mode and Effect Analysis.

Here are synopses of two studies aimed at quantifying preanalytical errors which can be reduced by continuous education and FMEA approaches. In a study of data from 105 laboratories and 4,715,132 tubes during the data collection period, according to determinations by clinicians in the request form, 32,977 (0.7%) were found to be rejected. Whole blood-EDTA samples and serum samples accounted for 76% of all samples collected among laboratories, although they corresponded to only 56% of all rejections. In total, 81% of rejections arose as a result of the following reasons:

  • "specimen not received" (38%),
  • "hemolysis" (29%), and
  • "clotted sample" (14%).

Moreover, plasma-citrate-erythrocyte sedimentation rate exhibited the highest percentage of rejection (1.5%), whereas the lowest rate corresponded to whole blood-EDTA (0.38%).

During a 1-year period, a total of 168,728 samples and 88,655 requests forms were received in a Stat laboratory. The total number of preanalytical errors was 1457, accounting for 0.8% of the total number of samples received in a year. Of the total preanalytical errors, 46% were hemolysed samples (biochemistry), 43% were clotted samples (hematology), 6% were samples lost-not received in the laboratory, 2.9% samples showed an inadequate sample-anticoagulant ratio, 0.7% were requests with errors in patient identification, 0.3% were samples collected in blood collection tubes with inappropriate anticoagulant and 0.1% were requests with errors -- missing test requests.


  1. Alsina MJ, Alvarez V, Barba N, et al. Clin Chem Lab Med. 2008;46(6):849-54.
  2. Grecu DS, Vlad DC, Dumitrascu V. Lab Med. 2014 Winter;45(1):74-81.
  3. Agarwal R. Indian J Clin Biochem. 2013 Jul;28(3):227-34.

For more on Failure Mode and Effect Analysis (FMEA) see http://asq.org/learn-about-quality/process-analysis-tools/overview/fmea.html and http://www.ihi.org/resources/Pages/Tools/FailureModesandEffectsAnalysisTool.aspx

posted by David Plaut


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