Diagnostic errors continue to be a source of preventable harm. Researchers in this study developed and implemented electronic triggers (e-triggers) to identify missed opportunities for diagnosis (MOD) in Veterans Affairs emergency departments (ED) between 2016 and 2020. The e-triggers targeted six clinical scenarios: high-risk stroke, high-risk abdominal pain, unexpected ED or hospital return, concerning symptom-disease dyads (e.g., heart attack within 7 days of ED visit for chest pain), and lack of follow-up after abnormal test results. In a sample of 8.7 million treat-and-release ED visits, e-triggers showed modest positive predictive value (from 11.0% to 52.4%). The researchers found that most MODs (83%) involved process breakdowns during the clinician-patient encounter, such as failure to complete a physical examination or review previous documentation.