some still say, "I have a doctor's visit", even though it is really a 'patient's visit' or 'a visit to the doctor' they mean.

Good insight, B-Y.

The same people who say they have a "doctor's visit" probably say they have a "dental appointment".

I'm not a doctor but your question seems to be more linguistic in nature than medical.

"Doctor's visit" is probably a hold-over from the days when doctor's actually made house calls, whereas dentists rarely did.

What is this called?

An anachronism? Or perhaps a vestigial expression? *

A recent headline in the Detroit News uses the term "doctor's visit" so it's still a common expression, at least with patients.

How to get the most out of your doctor's visit
Give your health care a boost with these tips for better communication
Detroit News, April 27, 2005

The responsibility for a good encounter lies with both the patient and the physician, says Dr. Denise White-Perkins, a family practitioner at Henry Ford Medical Center-Detroit Northwest and the director of the Institute on Multicultural Health at Henry Ford Health System.

"Every medical encounter is a cross-cultural encounter," White-Perkins says. "The physician is coming from a medical culture, which has its own language and set of expectations. The patient is not familiar with that culture. That difference can be magnified if there is also a gender difference, for example, or a communication gap."

White-Perkins says the idea that communication is key is gaining popularity among today's doctors, who see patient care as a potentially lifelong partnership between two people that is enhanced by trust and honesty.

"It's so important to have a good personal physician, someone you see regularly, to be a partner in your health and to really plan an active role," White-Perkins says.

http://snipurl.com/gnzj

* Dictionary.com Main Entry: ves·tig·ial
Pronunciation: ve-'stij-(E-)&l
Function: adjective
: of, relating to, or being a vestige <a vestigial structure> —ves·tig·ial·ly /-E/ adverb