What is "differential diagnosis"

Diagnosis \Di`ag*no"sis\, n.; pl. Diagnoses. [NL., fr. Gr. ?, fr. ? to distinguish; dia` through, asunder + ? to know. See Know.]

1. (Med.) The art or act of recognizing the presence of disease from its signs or symptoms, and deciding as to its character; also, the decision arrived at.

2. Hence, the act or process of identifying the nature or cause of some phenomenon, especially the abnormal behavior of an animal or artifactual device; as, diagnosis of a vibration in an automobile; diagnosis of the failure of a sales campaign; diagnosis of a computer malfunction.

3. Scientific determination of any kind; the concise description of characterization of a species.

4. Critical perception or scrutiny; judgment based on such scrutiny; esp., perception of, or judgment concerning, motives and character.

   The quick eye for effects, the clear diagnosis of men's minds, and the love of epigram.
   --Compton Reade.

   My diagnosis of his character proved correct.
   --J. Payn.

   Differential diagnosis (Med.), the determination of the distinguishing characteristics as between two similar diseases or conditions.

n. 1 (context medicine English) The process of determining which disease, from a set of possible candidates, is causing a patient's symptoms. 2 (context medicine English) A list of the common causes of a primary symptom.

n. a systematic method of diagnosing a disorder (e.g., headache) that lacks unique symptoms or signs

In medicine, a differential diagnosis is the distinguishing of a particular disease or condition from others that present similar clinical features. Differential diagnostic procedures are used by physicians and other trained medical professionals to diagnose the specific disease in a patient, or, at least, to eliminate any imminently life-threatening conditions. Often each individual option of a possible disease is called a differential diagnosis (for example, bronchitis could be a differential diagnosis in the evaluation of a cough that ends up with a final diagnosis of common cold).

More generally, a differential diagnostic procedure is a systematic diagnostic method used to identify the presence of a disease entity where multiple alternatives are possible. This method is essentially a process of elimination or at least a process of obtaining information that shrinks the "probabilities" of candidate conditions to negligible levels, by using evidence such as symptoms, patient history, and medical knowledge to adjust epistemic confidences in the mind of the diagnostician (or, for computerized or computer-assisted diagnosis, the software of the system).

Differential diagnosis can be regarded as implementing aspects of the hypothetico-deductive method, in the sense that the potential presence of candidate diseases or conditions can be viewed as hypotheses that physicians further determine as being true or false.

Common abbreviations of the term "differential diagnosis" include DDx, ddx, DD, D/Dx, or ΔΔ.