Red herring is something that misleads or distracts the physician from their original and organized thought towards the patient’s diagnosis and confuses them.
For example, you are assessing a child with a headache and thinking about the different possible diagnoses. The mother then says: “I forgot to mention that his uncle has malaria”. Are the two pieces of information related to each other? Probably not, but if you start thinking about Malaria instead of the child’s headache, you might get confused as the Malaria is actually a ‘red herring’.
The legends has it that smart hound dog owners used to test them during hunting missions by spreading red herrings along the hunting track so as to see if the hound dogs would get confused about the main prey target and go after the red herring instead.