Sign (medical)

In medicine, a sign is an objective observation, on physical examination or other test, that indicates a specific abnormality. They complement symptoms, the subjective description by the patient of his own experience. Symptoms come from history-taking while signs come from physical examination, imaging, blood analysis, etc.

"I have the worst headache of my life" is a symptom, and one that a competent professional doing triage would consider an emergency, at least until the blood pressure was taken. "Blood pressure is 240/180" is a sign, and an extremely critical one.

Signs often carry "eponyms", or the name of the clinician that first described them. For example, Tinel's sign, suggestive of a nerve entrapment, results when the patient reports tingling or pain when the path of the nerve is gently tapped. An abnormal response on physical examination, such as the failure of the pupils to contract when a light is shined into the eye, would be a sign.