"Oh, by the way," the patient says.
What comes next could be as innocuous as a harmless freckle — or a bombshell.
"You're walking out the door and they say 'Oh, I've got this chest pain I meant to tell you about,' so you have to go back into the room and start over again," said Dr. John Bonavia, a family doctor at Columbia St. Mary's-River Glen clinic in Milwaukee.
Doctors call it "the doorknob phenomenon."
Doctors' rushed schedules and patients' natural reluctance to reveal frightening or embarrassing symptoms make those questions at the doorknob almost inevitable, but medical schools increasingly are teaching students how to avoid such situations.
Dr. Rita Charon, who runs the narrative medicine program at Columbia University's medical school, said the phenomenon might even be one reason that doctors' visits often don't start on time — the previous patient may have had a doorknob question requiring another exam.
Part of Charon's program encourages doctors-in-training to listen and better "read" patients and their greatest concerns.
"You really have no idea of what part of life is going to come up and you really need to signal some desire to hear about it," Charon said.