Introduction and Context
Diagnosis is the foundation of clinical decision-making in the emergency department (ED). Rapid, accurate, and well-communicated diagnostic reasoning directs appropriate treatment, disposition, and follow-up. Yet diagnostic breakdowns—delays, inaccuracies, and communication failures—remain a leading cause of preventable harm. Recognizing the need for operational, ED-specific terminology to support research and quality improvement, a multidisciplinary expert panel used a modified RAND/UCLA method to develop formal definitions of two central concepts: diagnostic excellence and missed diagnostic opportunity (MDO). Their work, published in Annals of Emergency Medicine (Berdahl et al., 2026), translates conceptual components into practical language designed to be used in research, measurement, and safety programs.
