Differential Diagnosis - Specific Methods

Specific Methods

There are several methods for performing a differential diagnostic procedure, and several variants among those in turn. Furthermore, a differential diagnostic procedure can be used concomitantly or switchingly with protocols, guidelines or other diagnostic procedures (such as pattern-recognition or using medical algorithms).

For example, in case of medical emergency, there may not be enough time to do any detailed calculations or estimations of different probabilities, in which case the ABC protocol may be more appropriate. At a later, less acute, situation, there may be a switch to a more comprehensive differential diagnostic procedure.

The differential diagnostic procedure may be easier in the finding of a pathognomonic sign or symptom, in which it is almost certain that the target condition is present, and in the absence of finding a sine qua non sign or symptom, in which case it is almost certain that the target condition is absent. In reality, however, the subjective probability of the presence of a condition is never exactly 100% or 0%, so in reality the procedure is usually aimed at specifying the various probabilities in order to form indications for further actions.