diagnoosis

Diagnosis is the determination of which disease or condition explains a person’s signs and symptoms. It integrates medical history, physical examination, and usually a sequence of tests to identify a condition with reasonable certainty so that treatment and prognosis can be planned. The spelling diagnoosis is a common misspelling; the correct term is diagnosis.

Clinical diagnosis relies on patient-reported symptoms and observed signs, while objective data from laboratory tests, imaging studies, and pathology help confirm or refine it. A clinician often develops a differential diagnosis, a prioritized list of possible conditions that could explain the presentation, and uses tests to narrow the possibilities. A provisional diagnosis may be made early, with revision as new information becomes available; a final diagnosis is established when sufficient evidence supports a single condition.

Diagnostic methods include history-taking, physical examination, screening and specialty tests, laboratory analyses (such as blood tests and cultures), imaging (X-ray, ultrasound, CT, MRI), and tissue sampling (biopsy). Each method has limitations and characteristics described by sensitivity, specificity, and predictive values, and results must be interpreted in the clinical context.

Importance and challenges: An accurate diagnosis guides treatment choices, monitoring, and prognosis. Diagnostic errors can occur due to atypical presentations, overlapping symptoms, comorbidities, or cognitive biases. Ethical considerations include avoiding unnecessary testing, balancing risk and benefit, and ensuring informed patient involvement.

Examples illustrate common patterns: diabetes mellitus is diagnosed by glucose criteria, myocardial infarction by electrocardiography and biomarkers like troponin, and many cancers by biopsy confirming histological type. The process of differential diagnosis remains central to medical reasoning.