Members of the healthcare team have both a professional and moral obligation to ensure patient safety through the reduction and prevention of diagnostic error.  Medical errors have been recognized as the third leading cause of death, outnumbered only by cardiovascular events and cancer.1  In more specific terms, errors in the diagnostic process have been implicated as the cause of adverse events in 6-17% of hospitalized patients and 10% of patient deaths.It is imperative that clinical laboratory practitioners recognize the impact of diagnostic error on patient outcomes, as well as the complexity of identifying and preventing such events.

The first stage of prevention involves recognition of diagnostic error.  The National Academies of Science, Engineering and Medicine defines diagnostic error as “the failure to establish an accurate and timely explanation of the patient’s health problem(s) or communicate that explanation to the patient.”There are three primary categories of diagnostic error:  missed, wrong, or delayed diagnosis consequently causing harm to the patient.The three categories overlap significantly making them somewhat difficult to distinguish.  Missed diagnosis refers to instances where a patient’s chief medical complaint is not explained and thus the patient is not diagnosed. The second category, wrong diagnosis, occurs when the patient is incorrectly diagnosed, and the correct diagnosis is later revealed.  In contrast, a delayed diagnosis occurs when symptoms are not promptly diagnosed, and the patient’s condition worsens.4

The prevalence and economic cost of diagnostic error in today’s healthcare environment is notable.  According to the World Health Organization, diagnostic errors are more common in primary care, and a majority of medical patients will be subjected to some form of diagnostic error in their lifetime.Diagnostic errors have an estimated cost of $750 billion annually in the United States.One study estimated that each year more than 5% of adults seeking outpatient care in the United States experience some form of diagnostic error.Another quality improvement study that focused solely on pediatric patients revealed that diagnostic error affected 54% of patients with high blood pressure and 11% of patients having abnormal laboratory values involving microcytic anemias, elevated lead levels, group A Streptococcus infection and thyroid conditions.  The same study revealed that 62% of adolescents with depression did not receive appropriate action from their primary care physician.7 Failure to diagnose conditions such as psychological disorders and communicable disease increases the economic burden of diagnostic error while also presenting significant public health risk.8

Systems for measuring diagnostic error create yet another hurdle in the fight for prevention.  It is often difficult to define and measure diagnostic error due to challenges such as varying stages of disease progression, differentiation between overdiagnosis and underdiagnosis, as well as the retrospective nature of identifying diagnostic error.When a physician makes a mistake in diagnosis, the true impact may not be realized until years later, thereby adding to the conundrum of detecting and measuring error rates.The current healthcare environment also restricts transparency and acknowledgement of diagnostic errors, often making it impossible for members of the healthcare team to learn from previous events.It is also important to note that patients with advanced health conditions may require consults from several different providers making it difficult to consolidate all of the information needed to make an appropriate diagnosis, while also creating a structure that makes it difficult to determine exactly where diagnostic error originated.

The development of quality improvement initiatives to combat the occurrence of diagnostic errors requires a multifaceted approach.  Steps to reduce diagnostic error include promotion of teamwork, education and training that focuses on the diagnostic process, advanced use of health information technology, implementation of processes to identify and learn from near misses, creation of a work culture that supports improvement in the diagnostic process, development of reliable reporting systems and payment structures that promote coordination of care, and research funding to study the impact, occurrence and prevention of diagnostic error.Use of diagnostic teams can also be advantageous in decreasing the occurrence of diagnostic error.  The clinical laboratory can play a key role in the diagnostic team approach by offering guidance for providers regarding laboratory test selection and result interpretation.1  Diagnostic teams also help to decrease improper utilization of laboratory testing that can result in overdiagnosis, which can lead to a patient being correctly diagnosed for a disease that would never cause symptoms or being labeled with a specific diagnosis that they actually do not have.9, 10

Clinical laboratory practitioners have a unique opportunity to positively influence the reduction of diagnostic error.  Improper test utilization, laboratory error, and delay in transmission of test results can inadvertently lead to diagnostic error.  Education, coordination and improved collaboration between members of the healthcare team, as well as the patient, can greatly reduce the occurrence of errors leading to wrong or delayed diagnosis and treatment.  Through ongoing evaluation of decision making and systematic deficiencies, we can each play a part in promoting a philosophy of change and progress in diagnostic practice.


  1. Laposata, M. (2018).  The definition and scope of diagnostic error in the U.S. and how diagnostic error is enabled.  Journal of Applied Laboratory Medicine, 3(1):  128-134.  doi:  1373/jalm.2017.025882
  2. Institute of Medicine. (2015).  Improving diagnosis in health care – Quality chasm series (report in brief).  The National Academies of Sciences, Engineering and Medicine Press.  Available at:
  3. World Health Organization. (2016). Diagnostic errors.  Available at:;jsessionid=3D8A5ED5452430E66BBBF4FBAF55C654?sequence=1
  4. Society to Improve Diagnosis in Medicine. (2019). What is diagnostic error?  Available at:
  5. Pinnacle Care. (2016). The human cost and financial impact of misdiagnosis.  Available at:
  6. Singh, H., Meyer, A., & Thomas, E. (2014). The frequency of diagnostic errors in outpatient care: estimations from three large observational studies involving US adult populations. BMJ quality & safety23(9), 727–731. doi:10.1136/bmjqs-2013-002627
  7. Rinke, M. L., Singh, H., Heo, M., Adelman, J. S., O’Donnell, H. C., Choi, S. J., … Bundy, D. G. (2018). Diagnostic errors in primary care pediatrics: Project RedDE. Academic pediatrics18(2), 220–227. doi:10.1016/j.acap.2017.08.005
  8. Khullar, D., Jha, A., & Jena, A. (2015).  Reducing diagnostic errors – Why now?  New England Journal of Medicine; 373(26):  2491-2493.  doi:  1056/NEJMp1508044
  9. Zwaan, L. and Singh, H. (2016).  The challenges in defining and measuring diagnostic error.  Diagnosis;  2(2):  97-103.  doi:  1515/dx-2014-0069. 
  10. Balogh, E., Miller B., & Ball, J. (2015). Improving diagnosis in health care: Overview of diagnostic error in health care. National Academies Press.  Available at:

About The Author

Pamela Meadows, Ed.D., MT(ASCP)   Pamela Meadows is a member of the American Society for Clinical Laboratory Science (ASCLS) Patient Safety Committee and President of the West Virginia Society for Clinical Laboratory Science.  She has twenty-two years of experience as a clinical laboratory practitioner and is currently an Associate Professor in the Clinical Laboratory Sciences Department at Marshall University in Huntington, West Virginia.  Prior to teaching, she spent five years as a general laboratory supervisor and point-of-care testing coordinator. _______________________________________________________________________________________________ Rose Hanna, MS, MLS(ASCP)CM Rose Hanna is a member of the American Society for Clinical Laboratory Science (ASCLS) Patient Safety Committee. She is currently in her residency year for the Doctorate in Clinical laboratory science (DCLS) program at Rutgers University, New Jersey.  She has eight years of experience as a generalist with a concentration in Microbiology.

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