"Doctor, I want you to assume the following facts are true..."
"Assuming those facts are true, would you agree that failing to do X,Y,Z would be a departure from good medical practice?"
"If the doctor failed to do 'X" can we agree that would be a departure from good medical care?"
"I want you to assume that Dr. Jones did not recognize 'ABC'. As a result the patient suffered 'XYZ'. Can we agree, in that instance that would be inappropriate?"
A hypothetical question asks the doctor to assume facts in evidence that are favorable to our side.
Likewise, the defense has an opportunity to ask the doctor similar hypothetical questions that favor the defense.
Ultimately, it will be up to the jury to decide which set of assumed facts they believe took place. Then, based up those facts, they will now have testimony that either supports those facts or opposes them.