Treatment begins only after the problem has a name. Diagnosis is the process of identifying a disease or condition from its signs, symptoms, history, and the results of examinations and tests.

Clinicians gather data, generate differential possibilities, and refine them through targeted investigation. Pattern recognition and probabilistic reasoning both play roles. Diagnostic error remains a significant source of preventable harm, so systematic approaches and second opinions are used in difficult cases.

A working diagnosis guides initial management while further information is gathered. Final diagnosis may require tissue, imaging, or laboratory confirmation. Clear communication of the diagnosis, its certainty, and the next steps helps patients participate in decisions.

• Identification of disease from clinical and test data
• Involves history, examination, and investigations
• Refines differential possibilities to a working conclusion
• Guides treatment and patient communication