■ Safety of care:

Improving patient safety and reducing risks

Avoiding pitfalls in the emergency department: Recognizing and managing risks of diagnostic error

6 minutes

Published: December 2018

The information in this article was correct at the time of publishing

Physicians treating patients in the emergency department (ED) strive to make the most likely diagnosis, while frequently contending with complicating factors such as complex triaging, transitions in care, interruptions, crowding, and fatigue. An inadequate differential diagnosis, however, can mean a potentially serious condition is missed.

Among legal cases closed by the CMPA in the past five years, diagnostic error was the most common criticism of emergency physicians made by peer experts reviewing the cases.1 Between 2013 and 2017, the CMPA closed 486 legal cases in which patients or families alleged there was a wrong, missed, or delayed diagnosis by an ED physician. In 251 cases, peer experts were critical of a physician’s diagnostic process in the ED—and nearly all these cases resulted in patient harm, including death. The most prevalent contributing factor in the CMPA legal cases, based on peer expert opinion, was a physician’s inadequate clinical assessment of a patient.1

What is diagnostic error?

Diagnostic error is a "failure to establish an accurate and timely explanation of the patient’s health problem, or to communicate that explanation to the patient."2

Case example

An unstable patient with atrial fibrillation is misdiagnosed as a typical, uncomplicated case

An older woman with extensive cardiac co-morbidities—including congestive heart failure with severe left ventricular dysfunction—presents to the ED in a wheelchair following an in-hospital, pre-operative anaesthesia consultation for valve replacement surgery. She carries her ECG from that morning, showing rapid atrial fibrillation, and the anesthesiologist’s consultation note mentioning her grey skin colour. On initial assessment, an ED physician notes the ECG along with the patient’s blood pressure of 80/40 and heart rate of 160. She orders a nurse to administer 25 milligrams of intravenous diltiazem in two divided doses and then leaves to attend to other patients. The nurse administers the first dose and within minutes, the second dose. The patient soon becomes more hypotensive and nauseated. The nurse calls the ED physician, but the patient progresses to pulmonary edema and cardiogenic shock. During a three-week ICU stay—requiring intubation, vasopressors, renal dialysis, and an intra-aortic balloon pump—her ventricular function gradually improves.

What did the experts say?

In this case, the CMPA paid a settlement to the patient on behalf of the ED physician. Peer experts3  commented on the care provided.Based on the medical record, these experts opined that the ED physician did not take the time to obtain an appropriate medical history from the patient and, as a result, did not appreciate the extent of her pre-existing cardiovascular disease. Given the patient’s hypotension and extensive cardiac history, experts noted further that the ED physician should have supervised the diltiazem administration or considered a different management plan.

Most common expert criticisms

Peer experts retained by the parties in the CMPA legal cases most commonly criticized ED physicians for failing to ascertain an adequate medical history and physical exam, and for not ordering adequate diagnostic testing and sufficiently following up.

Inadequate medical history and physical exam

In approximately 60% of the CMPA cases in which there was expert criticism of the ED physician, peer experts opined that the ED physician performed an inadequate physical exam or obtained an overly limited medical history, as illustrated in the case example.

Multiple patient and system factors contributed to the outcomes. Many patient conditions were rare, atypical, difficult to detect, or prone to "search satisficing bias."4 For example, among patients with fractures, about 40% presented with multiple injuries.

Common biases: Search satisficing, premature closure

There are more than 40 types of cognitive biases that influence clinical decision-making in the ED. Common types include "search satisficing bias," which involves calling off the search once something is found, and "premature closure," which involves accepting a diagnosis before it has been fully verified.4

Resource shortages were also contributing factors. For example, experts criticized one ED physician for discharging a trauma patient with co-morbidities from a busy ED "hallway bed" with only one vital sign measurement, at triage. Another ED physician treated a patient’s laceration, but the ED was busy at the time and no charting was made of the visit.

Common patient conditions in CMPA legal cases (closed, 2013-2017) with expert criticism of the diagnostic process.  Fracture: 49 cases; Non-fracture musculoskeletal injury: 22 cases; Acute coronary syndrome: 23 cases; Arterial or venous embolism: 11 cases; Aortic aneurysm: 10 cases; Stroke: 10 cases; Infection, no sepsis: 33 cases; Sepsis: 16 cases

Experts in these cases commonly noted underestimating a patient’s risk level or not investigating key symptoms or concerns raised by a patient or family members. Consequently, ED teams failed to implement clinical protocols in a timely manner, such as a sepsis protocol. Sometimes, patients made repeat visits to the ED for the same condition as symptoms persisted or evolved. For example, a patient developing necrotizing fasciitis visited the ED three times within days, each time with worsening symptoms. Experts felt that by the second visit the ED physician should have further investigated the cause of the patient’s unexplained, intolerable pain.

In some cases, experts criticized a consultant or a nurse for not relaying important aspects of a patient’s history to the ED physician. There were also criticisms of ED physicians for not reading the medical record for a patient handed over to them. Other pitfalls included ED physicians not communicating crucial monitoring instructions to nurses, or not expressing the severity of a patient’s condition to another ED physician at handover.

Inadequate diagnostic testing and follow-up

Inadequate diagnostic testing was the second-most common criticism of ED physicians, occurring in nearly 50% of the cases reviewed. Peer experts noted ED physicians failing to order important diagnostic tests (including follow-up tests when appropriate), or relying on sub-optimal test results such as X-rays that were missing a clinically relevant field of view. In some cases, experts felt the ED physician should have applied a clinical decision rule to assess the need for diagnostic imaging.

In other cases experts opined that an ED physician took too long to review, or failed to act on, a significant test finding. These cases included ED physicians who misinterpreted or misread a test result. Some physicians failed to follow up in a timely manner on discrepant reports sent by a radiologist. Experts also identified faulty hospital systems that directed test results to the wrong physician, or failed to notify a physician or patient about a test result.

Risk management strategies

Peer experts acknowledge that diagnosing patients in a resource-restricted ED is difficult. Yet, expert opinions in the CMPA legal cases are consistent with the following strategies for lowering your medical-legal risk:

  • Gather an appropriate medical history of the patient, and conduct and document an appropriate, focused physical exam.
  • Be familiar with clinical practice guidelines and clinical decision rules for investigating common conditions encountered in the ED.
  • When a patient returns to the ED, re-evaluate the diagnostic assumption and consider a repeat history and physical exam with full vital signs.
  • Consider using a structured communication approach or tool for handovers.
  • Be familiar with your ED’s and hospital’s system for managing test results and promptly advise appropriate personnel of system deficiencies.

The bottom line

Diagnostic error is an inherent risk of working in the ED. It arises from cognitive and system factors that are often intertwined.5, 6 Fortunately, there are ways to mitigate medical-legal risk from diagnostic error, such as recognizing your cognitive biases7and documenting your clinical thinking in the medical record. Consider advocating for reliable systems and effective teamwork8, 9 in your ED to better communicate diagnoses between physicians, nurses, diagnostic labs, and patients.


  1. Includes physicians specializing in emergency medicine, residents working in the ED, and other physicians practising emergency medicine in the ED.
  2. Improving Diagnosis in Health Care [Internet]. Washington DC: The National Academies of Sciences, Engineering, and Medicine; 2015 [cited 2018 July 25]. Available from: https://www.nap.edu/catalog/21794/improving-diagnosis-in-health-care
  3. Peer experts refer to physicians retained by the parties in a legal action to interpret and provide their opinion on clinical, scientific, or technical issues surrounding the care provided. They are typically of similar training and experience as the physicians whose care they are reviewing.
  4. Croskerry P. Chapter 32: Cognitive and affective dispositions to respond. In: Cosby KS, Schenkel SM, Wears RL, editors. Patient Safety in Emergency Medicine. Philadelphia (USA): Lippincott Williams & Wilkins; 2009. p.219-27
  5. Kachalia A, Gandhi TK, Puopolo AL, et al. Missed and delayed diagnoses in the emergency department: a study of closed malpractice claims from 4 liability insurers. Ann Emerg Med. 2007;49(2):196-205
  6. Okafor N, Payne VL, Chathampally Y, et al. Using voluntary reports from physicians to learn from diagnostic errors in emergency medicine. Emerg Med J. 2016;33(4):245-52
  7. Clinical reasoning toolkit - Reducing Cognitive Error [Internet]. Evanston(USA): Society to Improve Diagnosis in Medicine [cited 2018 July 25]. Available from: https://www.improvediagnosis.org/general/custom.asp?page=Remedies.
  8. Graber ML, Rusz D, Jones ML, et al. The new diagnostic team. Diagnosis (Berl). 2017;4(4):225-38
  9. Schiff GD. Diagnosis and diagnostic errors: time for a new paradigm. BMJ Qual Saf. 2014;23(1):1-3

DISCLAIMER: The information contained in this learning material is for general educational purposes only and is not intended to provide specific professional medical or legal advice, nor to constitute a "standard of care" for Canadian healthcare professionals. The use of CMPA learning resources is subject to the foregoing as well as the CMPA's Terms of Use.