Clinical Assessment and Diagnosis
Building the Diagnostic Frame
Clinical assessment begins with a structured history and a focused physical examination, then moves to hypothesis generation. Candidates must understand the components of a complete history (chief complaint, history of present illness, past medical and surgical history, medications and allergies, family and social history, review of systems), the purpose of each examination maneuver, and how findings are grouped into syndromes before a differential is narrowed. Know the difference between screening, diagnostic, and monitoring tests, and the concepts of sensitivity, specificity, positive and negative predictive value, and how prevalence shifts predictive value. Recognize classic patterns: acute versus chronic onset, unilateral versus bilateral findings, and constitutional symptoms that raise concern for serious disease.
Traps in Examination Questions
Common traps include confusing a risk factor with a diagnostic criterion, choosing the most sensitive test when the question asks for confirmation (specificity), and ignoring pretest probability. Another frequent trap is the anchoring bias question, where an early plausible diagnosis suppresses a red-flag finding. Watch for wording such as "most likely" versus "most appropriate next step": the first asks for epidemiology, the second for process. Also distinguish definitive diagnosis from clinical diagnosis when no gold standard exists.
Worked Example
A rule of thumb: when a question asks what test to order next, first ask whether the patient is stable and whether the diagnosis is already clinically evident. If the condition is a bedside diagnosis, additional testing is for complications or confirmation, not diagnosis. For a patient with pleuritic chest pain and unilateral leg swelling, the pretest probability for pulmonary embolism is high enough that the next step is definitive imaging rather than a D-dimer, which is best used to rule out disease in low-probability patients.