Differential diagnosis - Definition and Overview

Differential diagnosis is the process by which a doctor arrives at diagnosis in complicated medical problems. It is more systematic than the old-fashioned method of diagnosis by gestalt (impression).

After performing a medical interview (history) and a physical examination, the doctor collates the abnormal findings and (for each of them) makes a list of the most likely causes. In the general setting, these lists are each about 3-4 items long.

When this process has been completed, medical imaging or blood tests may help to eliminate possible causes, until the most likely cause becomes the arrived diagnosis.