To effectively address diagnostic improvement, clinicians should understand some concepts around how people reason and the common pitfalls that can lead to errors, explains Joe Grubenhoff, MD, medical director of the diagnostic safety program at Children’s Hospital Colorado in Aurora. For example, one commonly observed cognitive bias is triage queuing. This happens when early during a clinical encounter, a patient receives a diagnosis that firmly establishes his or her care trajectory, shutting off any consideration of alternative diagnoses as the patient advances through the specified workup.

Grubenhoff recalls a case in which a young girl presented to the ED with what seemed like psychotic features. “There was a vague history of her recently using marijuana for the first time. She basically got put in a pathway of being worked up for a psychiatric concern,” he explains.

Specifically, the provider’s diagnosis was cannabis-induced psychosis. Once that label was applied to this patient that was the focus throughout the clinical encounter. But this diagnosis was incorrect. The patient was eventually diagnosed with anti-NMDA receptor encephalitis, a rare auto-immune inflammation that occurred in response to a benign ovarian teratoma.

How might case reviewers address such an error with the provider? “They might say that [he or she] should have known better, that the patient still needed a broad differential and maybe a workup before just assuming that the patient had psychosis from marijuana,” Grubenhoff offers.

However, he suggests a more effective approach would be to help the provider understand how triage queuing may explain what was going on in his or her mind when managing this case. This is where cognitive psychology enters the conversation.

“This doesn’t happen to just one person; it could have happened to any provider in that same scenario because of the way the human mind works ... the provider [develops] an understanding of where his thinking might have gone wrong,” Grubenhoff says.

The issue becomes less about the individual provider and more about the systems of reasoning that humans employ. It gives the provider something he or she can address going forward. Specifically, the next time a patient comes in with what looks like psychiatric symptoms, the provider should keep his or her differential diagnosis broad.

“Avoiding diagnostic errors is a challenge. Most of the time, we actually do a reasonably good job, and a lot of the errors that we make, we make subconsciously,” Grubenhoff shares. “We don’t even realize that we are making them.”

Research suggests the largest body of adverse events in emergency medicine is caused by a combination of cognitive errors and systems errors.1 “These things don’t happen in isolation. We have to be cautious that when we are talking about the human part of this, the decision-making and the diagnosis, that we don’t ignore the systems part of it. Those two things [affect] one another,” Grubenhoff says. 


  1. 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;33:245-252.