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HiQuiPs: Optimizing your diagnostic reasoning – themes from CMPA medico-legal cases

Updated: Oct 9, 2022

A 49-year-old male presents to the emergency department with shortness of breath on exertion and left lower chest discomfort for the past 3 days. His past medical history is significant for hypertension and he has a family history of heart disease. At triage he is noted to have a pulse of 117 and normal blood pressure. His oxygenation is 94% on room air. His cardiac and respiratory exam are normal, and no other abnormalities are noted, including no leg swelling. The physician notes a normal EKG and CXR and negative serial cardiac enzymes. The patient is diagnosed with atypical chest pain and discharged home with outpatient cardiac follow-up. The patient subsequently collapses at home and is transferred to the hospital. He is diagnosed with large bilateral pulmonary emboli and admitted to hospital.

What is diagnostic error?

Diagnostic errors arise from system, team, and individual factors that are often intertwined. They are an inherent risk of clinical practice and a common theme in CMPA closed cases. Diagnostic errors include delayed, missed, and wrong diagnoses. The inherent complexity of the diagnostic process means that even when errors are identified, learning from them can be challenging.(1)

The Canadian Medical Protective Association (CMPA) provides medico-legal liability protection and assistance to more than 105,000 physicians across Canada. Our mission is to protect the professional integrity of physicians and to promote safe medical care. Through ongoing analysis of our closed medico-legal cases (which include civil legal cases, College and hospital complaints), we are able to identify potential areas to further focus member education and support.

This summary of CMPA diagnostic error cases seeks to inform discussions on reducing diagnostic error by analyzing the provider, team, and system factors seen most frequently. By providing medico-legal data on factors that affect diagnostic reasoning in healthcare practice, this information can help physicians to better understand, evaluate, and develop new processes to enhance their diagnostic skills.

Common types of diagnostic error

In order to identify common themes related to diagnostic error, we reviewed closed medico-legal cases for all specialties from 2016-2020 in which diagnostic error was identified as a factor that contributed to the event (n=3625). Generalist/family physicians (36.6%), emergency physicians (14.3%), and obstetrics and gynecologists (6%) featured most frequently in these cases.

Common examples of contributing factors to diagnostic error included:

1. Incomplete history or physical exams;

2. Failure to order relevant tests or imaging;

3. Failure to consult or refer to appropriate healthcare professionals;

4. Failure to follow-up on test results and referrals; and

5. Failure to develop a treatment plan with the patient.(2)

Frequent contributing factors to diagnostic error (source: CMPA)

The outcomes of diagnostic errors can vary, but a delay in diagnosis is often associated with risk of patient harm. In our review of CMPA cases due to diagnostic delay, 86.7% of cases resulted in a harmful incident – where a patient experienced healthcare-related injury that resulted from provider, team, or system errors, as identified by peer expert opinion. Of the cases that resulted in patient harm, 10% resulted in severe harm, and 14.6% resulted in death.(3)

Factors influencing diagnostic reasoning

Diagnosis is a complex process that “evolves over time with new inputs.”(4) Physicians must consider a broad range of diagnostic possibilities with varying probabilities. But the process of applying diagnostic reasoning can be impacted by both individual and systems issues.

Individual factors: knowledge gaps and cognitive biases

Diagnostic errors are often perceived to be the result of gaps in a physician’s knowledge and/or skills. This is often due to the complexity of the diagnostic process being intertwined with a physician’s “knowledge, clinical acumen, and problem-solving skills.”(5) Intrinsic factors such as cognitive biases have been well described in the diagnostic error literature as well in influencing a physician’s diagnostic reasoning. These biases include anchoring to one diagnosis or symptom in spite of evidence, prematurely accepting an initial diagnosis without considering other diagnoses, or failing to consider rare diagnoses.(6)

System factors: communication and a lack of resources

External (system) factors can also influence diagnostic reasoning. These can include delays in receiving critical patient information or test results, miscommunication between healthcare providers, or lack of resources. Systems errors may include policies or procedures that create error-prone situations, poor supervision of trainees, issues with communication or handover, or standardized processes that create unnecessary delays.(5)

Summing up: how to optimize your diagnostic reasoning

Diagnostic reasoning remains the cornerstone of medical care. By identifying individual, team and system factors that can affect the diagnostic reasoning process in CMPA medico-legal case data, we have an opportunity to help support and identify ways to mitigate potential risks for physicians. Through the CMPA’s ongoing education and research strategies, we will be better able to support physicians to meet current challenges in healthcare through quality improvement initiatives, and to promote patient safety.

Our hope is that, in writing this article, we have provided you with an understanding of some common causes of diagnostic error. As you reflect on your own clinical practice, we hope that you pay attention to the contributing factors to diagnostic error that may be present around you, and that you strive to detect – and improve – any knowledge gaps, biases and environmental factors that may be delaying you from receiving necessary information for making an accurate diagnosis.

Thanks for tuning in to another HiQuiPs post! As always, don't hesitate to let us know what you think on twitter @Hi_Qui_Ps. Be sure to follow @CMPAmembers for more insights, as well.

Senior Editor: Ahmed Taher

Copyedited by: Matthew Hacker Teper


1. Singh H, Graber ML, Hofer TP. Measures to improve diagnostic safety in clinical practice. Journal of Patient Safety. 2019 Dec;15(4):311-316. [Cited 2022 March 25] Available from: Measures to Improve Diagnostic Safety in Clinical Practice ( doi: 10.1097/PTS.0000000000000338

2. Note that our review of CMPA medico-legal cases reflects cases of which the Association is aware, and therefore may over- or underrepresent harm statistics.

3. In these diagnostic errors cases, the contributing factors most often identified were clinical decision-making (74.5%), situational awareness (49.4%), deficient assessment (48%) and failure to perform test/intervention (36.6%).

4. Kaplan M. Diagnosis is a process: experts offer advice on diagnostic error and delays in patient safety. 2016 Jan. [Cited 2022 March 24} Available from: Diagnosis Is a Process: Experts Offer Advice on Diagnostic Error and Delays in Patient Safety | IHI - Institute for Healthcare Improvement

5. Graber ML, Franklin N, Gordon R. Diagnostic Error in Internal Medicine. Arch Intern Med. 2005;165(13):1493–1499. [Cited 2022 April 15]. Available from: Diagnostic Error in Internal Medicine | Health Care Safety | JAMA Internal Medicine | JAMA Network doi:10.1001/archinte.165.13.1493

6. Canadian Medical Protective Association Good Practices Guide. Cognitive Biases: Common Cognitive Biases [Internet]. Ottawa; CMPA. [Cited 2022 April 19]. Available from: CMPA Good Practices Guide - Common cognitive biases (

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