The United States Supreme Court has defined "an agreement 'implied in fact'" as "founded upon a meeting of minds, which, although not embodied in an express contract, is inferred, as a fact, from conduct of the parties showing, in the light of the surrounding circumstances, their tacit understanding.
In such a case, the court will probably find that (as a matter of fact) the parties had an implied contract.
If the patient refuses to pay after being examined, they will have breached the implied contract.
However, it may be more difficult to prove the existence and terms of an implied contract should a dispute arise.
In some jurisdictions, contracts involving real estate may not be created on an implied-in-fact basis, requiring the transaction to be in writing.