Errors in a Stat Laboratory: Types and Frequencies 10 Years Later

BACKGROUND: In view of increasing attention focused on patient safety and the need to reduce laboratory errors, it is important that clinical laboratories collect statistics on error occurrence rates over the whole testing cycle, including pre-, intra-, and postanalytical phases. METHODS: The present study was conducted in 2006 according to the design we previously used in 1996 to monitor the error rates for laboratory testing in 4 different departments (internal medicine, nephrology, surgery, and intensive care). For 3 months, physicians and nurses were asked to pay careful attention to all test results. Any suspected laboratory error was recorded with associated pertinent clinical information. Every day, a laboratory physician visited the 4 departments and a critical appraisal was made of any suspect results. RESULTS: Among a total of 51 746 analyses, clinicians notified us of 393 questionable findings, 160 of which were confirmed as laboratory errors. The overall frequency of errors, 3092 ppm, was significantly lower (P <0.05) than in 1996 (4700 ppm). Of the 160 confirmed errors, 61.9% were preanalytical errors, 15% were analytical, and 23.1% were postanalytical. CONCLUSIONS: During the last decade the error rates in our stat laboratory have been reduced significantly. As demonstrated by the distribution pattern, the pre- and postanalytical steps still have the highest error prevalences, but changes have occurred in the types and frequencies of errors in these phases of testing.