A doctor may not have thought about what findings he or she had used subconsciously to arrive at the list of possible diagnoses. This process is often described as ‘pattern recognition’, its result often being described as a ‘diagnostic impression’. (In the same way, if someone knocked on our door we would think of a number of possible visitors without be able to explain logically how we arrived at this list).
There is a simple device that can be used to generate a list of such possibilities in a logical and transparent way. It is called the diagnostic lead. It works like this. Each of the patient’s findings can be used to generate a list of possibilities. Some findings such as fatigue will generate a long list of possibilities that will take a long time to work through and is therefore impracticable. However, others such as rapid weight loss will have a much shorter list of possibilities, of which one would be onset of Type 1 Diabetes Mellitus. If prompted a doctor will be able to reflect and indicate which findings generated the shortest list of possibilities and how each could ‘lead’ him or her to the current diagnostic possibilities. The most important and useful diagnostic leads in medicine are described in the Oxford Handbook of Clinical Diagnosis.
© Huw Llewelyn 2016