The clinical laboratory plays a significant role in the effective diagnosis and treatment of patients.  Recent recommendations from the Institute of Medicine (IOM) suggest that patient safety can be improved through the reduction of diagnostic errors.  According to the IOM, diagnostic errors include delays in diagnosis, as well as the provision of “unnecessary or harmful treatment.”1 From a clinical laboratory standpoint, the delivery of timely and accurate test results ensures that providers have the information needed to formulate a correct diagnosis and treatment plan.

While most laboratory errors arise during the pre-analytical and post-analytical phases of testing, errors occurring in the analytical phase can have a detrimental effect on patient care.  The analytical phase of testing is described as activities occurring from the time of specimen preparation to result verification.2 Approximately 7-13% of laboratory errors occur during the analytical phase of testing.2   There are multiple areas of concern regarding the analytical phase, including interfering substances, reagent stability, calibration, performance and monitoring of quality control, instrumentation malfunction, as well as failure to follow standard procedures for both patient testing and equipment maintenance.

The following case study outlines a scenario involving laboratory error in the analytical phase of testing and demonstrates the profound impact such errors can have on patient care and safety.

Case Study:

  • Hospital X is a 200-bed community hospital serving a variety of patient populations. The hospital specializes in orthopedic surgeries, obstetrics, and oncology.  Trauma patients and those requiring advanced cardiac care are commonly stabilized and transferred to another local hospital for appropriate care.
  • Within the first hour of their shift, a senior Medical Laboratory Scientist (MLS) working evening shift notices an increase in the number of elevated Troponin I results. The MLS becomes alarmed by the result trend and suspects possible instrumentation error.
  • The MLS notifies the evening shift supervisor of the suspicious results. Upon investigation, the supervisor discovers that the elevated Troponins were all performed on the same chemistry analyzer.  She directs the MLS to perform quality control (QC) on the instrument in question.  The QC yields results outside of the acceptable range for several analytes, including Troponin I.
  • Review of maintenance and quality control records revealed that quarterly maintenance had been performed on dayshift that same day; however, there was no record of quality control after the maintenance procedures were performed.
  • As part of the quarterly maintenance, a series of instrument components were replaced. Visual examination of the instrument revealed a piece of tubing that was not properly connected, consequently leading to erroneously elevated test results for certain analytes.
  • After consultation with the dayshift chemistry supervisor, it was discovered that the maintenance was performed by a MLS who had recently transferred from midnight shift to dayshift. This was the employee’s first time performing quarterly maintenance since their initial training on the instrument more than two years prior.
  • Failure to properly follow manufacturer maintenance procedures and the laboratory quality control policy resulted in the verification of numerous erroneous test results over a 3-hour period.
  • Due to inaccurate laboratory results, the Director of Emergency Services noted that two patients had been transferred to another facility for emergency cardiac catheterizations, one patient had incorrectly been diagnosed and scheduled for renal consult, and two additional patients received improper pharmaceutical treatments.
  • Implications: At minimum, annual staff training and competency assessment for maintenance procedures performed on an infrequent basis, as well as quality control protocol, is suggested.


Analytical errors, such as the one described in the case study above, can lead to incorrect diagnosis and improper treatment decisions.  The use of case studies that include thought-provoking questions can be used for the education of staff, while building critical thinking skills to effectively troubleshoot errors in the analytical phase of testing.  While most laboratories have a plethora of mechanisms in place to verify the accuracy of the analytical phase and ensure the quality of testing, it is important to note the monumental importance that analytical errors play in patient safety.


  1. National Academies of Sciences, Engineering, and Medicine. (2015).  Improving diagnosis in health care.  Washington, D.C.:  The National Academies Press.


  1. Hammerling, J.A. (2012).  A review of medical errors in laboratory diagnostics and where we are today.  Laboratory Medicine, 43(2), pp. 41-44.