Practice of Medicine


Preventing Medical Errors by Improving the Diagnostic Process

By: Marshaleen King, MD

Executive Summary 

Diagnostic errors account for a significant number of preventable medical errors, yet physicians often only recognize them in hindsight. Reducing issues caused by diagnostic errors warrants a collaborative approach between physicians, patients and other members of the healthcare team. 

Recommended Actions  

  • Enhance communication between patients and providers to improve the quality of information gathered when making a diagnosis. 
  • Pay attention when test results don’t coincide with a suspected diagnosis and consider an alternative diagnosis. 
  • Ensure that patients receive follow-up consultations after obtaining test and lab results.  

Medical errors remain a major cause of morbidity and mortality. Recent estimates indicate that medical error is likely the third leading cause of death in the US, 1 with some sources reporting an incidence of 210,000 to 400,000 deaths annually due to medical errors among hospitalized patients. 2 

Although diagnostic errors have received less attention over the past decade compared to medication and procedural errors, they account for a significant number of preventable medical errors. The Institute of Medicine (IOM) report published in 2015, “Improving Diagnosis in Health Care,” placed a spotlight on diagnostic errors and emphasized the fact that diagnostic errors serve as a major source of avoidable medical errors. The IOM attributes the failure to recognize diagnostic errors as a significant cause of medical harm due in part to the fact that physicians often recognize diagnostic errors in hindsight. 3 

Factors Contributing to Diagnostic Errors 

Several aspects of the diagnostic process are vulnerable to mistakes, thus addressing diagnostic errors warrants a multifaceted approach. Analysis of medical errors over the years has revealed that medical errors are often the result of cognitive factors and/or system-related factors. 

Due to the numerous factors contributing to diagnostic errors, many institutions have had difficulty in developing tools to reduce errors and improve the diagnostic process. A recent publication by investigators from Houston, Texas, outlined a multifaceted framework for improving the measurement of diagnostic errors to enhance system-wide safety measurement and monitoring and to reduce diagnostic errors. 4 The authors proposed that systematically studying diagnostic errors and paying closer attention to the factors contributing to these errors will enable us to devise strategies to prevent diagnostic errors and improve the diagnostic process. 

Sources of diagnostic errors include: 

  • Breakdown in physician-patient communication, including taking an incomplete patient history and/or failing to obtain necessary tests 
  • Failure to utilize cognitive support tools such as information resources, risk-assessment tools and consultations 
  • Failure to properly use the chart/EHR to review and document data 
  • Failure to clearly designate patient responsibility to follow up on test results 
  • Lack of a reminder system to ensure follow-up on test results 

Enhancing the Diagnostic Process 

Mechanisms for avoiding diagnostic errors may be categorized based on the primary area of focus. Strategies targeting both cognitive and system-based errors are necessary to effectively reduce diagnostic errors. 5 

Recommendations for improving the diagnostic process include: 

  • Implementing a teamwork approach in the diagnostic process and employing methods that enhance communication between patients and medical professionals to improve on the quality of information gathered in making a diagnosis 
  • Keeping an open mind when investigating a problem (instead of narrowing down the differential too soon) to avoid anchoring bias 
  • Ensuring that healthcare professionals receive high-quality education and training in the diagnostic process 
  • Paying attention when things don’t add up, such as when test results don’t coincide with a suspected diagnosis, and considering an alternate diagnosis 
  • Following up on tests and ensuring that responsibility to act on test results has been clearly designated to avoid delays in making an accurate diagnosis 
  • Consulting specialists when necessary to guide the diagnostic process particularly for complex or uncommon conditions 
  • Involving patients and their family members in their care to ensure that follow-up tests and procedures occur as planned and the physician doesn’t miss changes in the patient’s condition 
  • Developing a system that permits near misses and errors to be identified and reported without fear of retaliation, then utilizing the information to avoid repeating errors 

Reducing the healthcare burden caused by diagnostic errors warrants a team approach with participation from physicians, patients and other members of the healthcare team. Although it is unlikely that diagnostic errors can be completely prevented, implementing the strategies and recommendations outlined above can lead to improvements in the diagnostic process and reduce the likelihood of diagnostic errors. 

Lessons Learned  

  • Ensure providers are receiving high-quality education, training, and continuing education regarding the diagnostic process. 
  • Consult other physicians or specialists when confronted by a complex diagnosis, uncommon condition or irregular test result.  
  • Ensure that patients know how and when to request follow-up care or consultations regarding test results.  

Potential Damages 

Failure to diagnose or delayed diagnosis are main causes for lawsuits against primary care physicians. A physician may be held liable for the injuries or losses that result from the delay or failure to diagnose. Implementing thorough diagnostic evaluations and follow up consultations regarding test results reduces the risks of missing or delaying a diagnosis and thus reduces the risk of costly litigation.   

[1] Makary M, Daniel M. Medical error—the third leading cause of death in the US. The BMJ. 2016;353(2139):10.1136/bmj.i2139.

[2] James JTA. A new, evidence-based estimate of patient harms associated with hospital care. Journal of Patient Safety. 2013;9:122-8.

[3] Institute of Medicine. Improving Diagnosis in Health Care. National Academies Press. 2015.

[4] Singh H, Sittig DF. Advancing the science of measurement of diagnostic errors in healthcare: the Safer Dx framework. BMJ Quality & Safety. 2015;24:103-10.

[5] Singh H, Zwaan L. Inpatient Notes: Reducing Diagnostic Error—A New Horizon of Opportunities for Hospital Medicine. Ann Intern Med. 2016 Oct 18;165(8):HO2-HO4. doi: 10.7326/M16-2042.


1. Diagnostic errors often occur when a provider receives an incomplete patient history.
2. Providers can always choose the first or most likely diagnosis when evaluating a patient.
3. Following up on tests and ensuring that patients know of the responsibility to act on test results helps avoid delays in making an accurate diagnosis.


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The information provided in this resource does not constitute legal, medical or any other professional advice, nor does it establish a standard of care. This resource has been created as an aid to you in your practice. The ultimate decision on how to use the information provided rests solely with you, the PolicyOwner.