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 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 (e.g. acute bronchitis could be a differential diagnosis in the evaluation of a cough, even if the final diagnosis is 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 may employ algorithms, akin to the 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, ΔΔ, or ΔΔ𝛘.
a differential diagnosis is also commonly used within the field of psychiatry/psychology, where two different diagnoses can be attached to a patient who is exhibiting symptoms which could fit into either diagnosis. for example, a patient who has been diagnosed with bipolar disorder may also be given a differential diagnosis of borderline personality disorder, given the similarity in the symptoms of both conditions.
strategies used in preparing a differential diagnosis list vary with experience of the healthcare provider. while novice providers may work systemically to assess all possible explanations for a patients concerns, those with more experience often draw on clinical experience and pattern recognition to protect the patient from delays, risks, and cost of inefficient strategies or tests. effective providers utilize an evidence-based approach, complementing their clinical experience with knowledge from clinical research.