Reducing Diagnostic Error in the Emergency Department

June 23, 2022

By Carolyn Anctil, MD, FACEP, Constellation Chief Medical Advisor

A 62-year-old man with insulin-dependent diabetes presented to the emergency department (ED) with fever and malaise during a local community COVID-19 surge. The ED physician ordered COVID-19 diagnostic testing according to the hospital’s protocols. The man tested positive for COVID-19, his COVID-19-associated hyperinflammatory syndrome score was low, and his COVID-19 stress test was negative. The ED physician noted that the man’s white blood cell (WBC) count was high at 18,000 with a left shift. He diagnosed the man with COVID-19 and discharged him home with instructions to return if not getting better.

Two days later, the man returned to the ED with complaints of worsening fever, malaise and right foot swelling. Another ED physician examined the man and diagnosed a severe infection in his right foot. She requested a surgical consult and admitted the man to the hospital. The man underwent surgical debridement and a partial amputation of his right foot due to diabetic foot osteomyelitis.

Diagnostic error in the emergency department

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

“Diagnostic errors are the most frequent risk that clinicians working in the ED face and are primarily triggered by clinical judgment factors (clinical thinking and decision-making) during the initial assessment.”

Carolyn Antcil, MD, FACEP, Constellation Chief Medical Advisor

An analysis of Constellation malpractice claim data demonstrates that diagnostic error is the #1 most frequent allegation of negligence and #1 most costly in the ED. Candello’s (a Division of CRICO) national database, which consists of closed medical professional liability (MPL) claims from multiple MPL insurers (including Constellation) and health systems, breaks down the top factors contributing to missed or delayed diagnoses in the ED:

These top contributing factors all occur during the initial diagnostic assessment. The top missed diagnoses in Candello’s ED claims are infection, infarction, embolism/thrombosis and fracture. In 60% of these cases, the patient injury was high severity or death.

Clinician thinking and decision-making

One way to mitigate the risk of diagnostic error is to understand a vulnerability in the diagnostic process of care: clinician thinking and decision-making. According to Dr. Pat Croskerry, cognitive dispositions to respond (CDR) is a term to encourage an analytical approach to why a clinician reached a particular diagnosis for a given patient under certain conditions.1 Croskerry identified a number of determinant factors that lead to a CDR such as: ambient conditions, affective state, past experience, team factors, patient factors and fatigue/sleep.

According to Dr. Chris Nickson, a single CDR may fall into one or more of the following categories2 as illustrated using the case above:

  • Error of being overly attached to a particular diagnosis. “His COVID-19 test is positive.
  • Error due to failure to consider an alternative diagnosis. “Why should I consider an alternative diagnosis when his COVID-19 test is positive.” This led to a narrow diagnostic focus and premature closure/discharge when alternative diagnoses for his fever and high WBC count were not considered.
  • Error due to inheriting someone else’s thinking. “A COVID-19 test was obtained in triage.
  • Errors in diagnosis prevalence. “He was seen during a COVID-19 surge so he must have COVID-19.
  • Errors involving patient characteristics or presentation context. “Most fevers at this time are due to COVID-19.”
  • Errors associated with a physician‘s unique personality or decision style. A likely diagnosis was found with a positive test, ignoring other abnormal lab tests such as the elevated WBC count. However, COVID-19 patients usually don’t have an elevated WBC count.
How to improve cognitive processing

Cognitive processing is a challenge in a busy ED because of the fast pace, heavy workload and repeated distractions. Most seasoned ED clinicians, whether they are aware of it or not, probably use a cognitive checklist. They should ask themselves:

  • What are the “not to miss” possible diagnoses?
  • Could this patient with COVID-19 have an alternative diagnosis that would explain his elevated WBC count?
  • Did I stop thinking and just accept the first diagnosis that came to mind?
  • Was this diagnosis suggested to me by someone else?
  • Is there other data I haven’t reviewed yet or explained?
  • Did something stop my thinking? Was I interrupted, distracted or overloaded when evaluating this patient? Was it the end of my shift or a handoff to another clinician?
  • Do I dislike the patient or like this patient too much, or know them personally?

It can be difficult, but it is important to force oneself to generate several diagnostic hypotheses and ask questions that are contrary rather than confirmatory. Utilizing clinical decision support tools can be very helpful to clinical thinking and reasoning. There are several robust clinical decision support systems that will suggest a list of diagnoses based on patient symptoms. Utilizing consultants or getting a second opinion from a peer may also open other diagnostic possibilities. “How often do you see a high WBC count in a patient with COVID-19?”

Employing a strategy to enhance empathetic communication with patients may help engage them in the diagnostic process. For example, in the case above, asking the patient, “Sir, is there anything else going on with you today?” could have elicited the response, “Well, my right foot is swollen.”

Developing a supportive peer feedback process can help ED groups learn from prior delays and missed diagnoses. This case of a patient with COVID-19 and an elevated WBC count was reviewed and shared in a supportive format within the ED group. Subsequently, there were multiple COVID-19 patients who had alternative diagnoses explored and treated.

The HEAL Prepare Toolkit

One component in Constellation’s HEAL program is to learn from each adverse event. Constellation shares a goal of partnering with our policyholders to help reduce diagnostic errors through early and open communication and learning.

The HEAL Prepare Toolkit will help assess your team’s readiness to communicate after a diagnostic error and move forward with learning. The Toolkit includes an assessment, best practices and sample tools. Start your journey by taking the HEAL Assessment. The Action Plan will then guide you through the Toolkit’s four units: (1) culture, (2) event response, (3) communicating after harm events, and (4) moving forward.

Sign in or register at to access the HEAL Prepare Toolkit found in Risk Resources.

Constellation’s HEAL program provides healing benefits for care teams and their organizations because we truly believe that what’s good for care teams is good for business.

Constellation® and HEAL® are trademarks of Constellation, Inc.


  1. Croskerry P. Diagnostic Failure: A Cognitive and Affective Approach. In: Henriksen K, Battles JB, Marks ES, et al., editors. Advances in Patient Safety: From Research to Implementation (Volume 2: Concepts and Methodology). Rockville (MD): Agency for Healthcare Research and Quality (US); 2005 Feb. Available from: Accessed April 20, 2022.
  2. Nickson C. Cognitive Dispositions to Respond. 2020. Available at,e.g.%20heuristics%2C%20biases%2C%20sanctions%2C. Accessed April 20, 2022.
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