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Why might doctors consider a less-likely diagnosis before a more common one?

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In the process of clinical decision-making, physicians typically rank potential diagnoses by likelihood. However, doctors may prioritize a less-likely diagnosis if it is life-threatening or could result in severe consequences if not addressed immediately.12

For example, a physician might first rule out a heart attack in a patient presenting with chest pain or appendicitis in a child with abdominal pain, even if a less serious condition is statistically more probable. This approach ensures that critical, time-sensitive conditions are not overlooked while the clinician continues to refine the differential diagnosis through further testing and evaluation.12