[David L.]

I consult my doctor.
I consult with my doctor.

These have slightly different meanings:
Most usually, people 'consult their doctor', as they are depending on him to know what to do to remedy some ailment.

But say I am going to use some herbal remedy from the health food shop, or start the latest fad diet using some meal-replacement drink I can buy at the supermarket.
Such products would say on the label for the buyer to "consult with your doctor" before taking (so as to be sure the doctor is not aware of any known health problem that the person has that would be a contraindication to using it, or that it won't conflict with any medication they are taking.) You are not asking him to diagnose anything, to prescribe anything, to heal or mend anything. You are simply consulting him for his expert advice and guidance about some external matter you are about to engage in.
In this way, 'consult with' is used in many situations in which people have discussions or confer with someone, before undertaking a course of action.
"We will have to consult with the board of directors before we can implement the plan."