We were recently pregnant with a baby with birth defects. We knew that there was a good chance that he would not be born alive due to the birth defects, so we decided to shell out the $200+ to see our son in 3-D/4-D ultrasound. This was at the recommended time according to Grand View's website, which is anytime after our diagnostic ultrasound.
I made an appointment with Grand View Ultrasound. In our discussion, it came up that our son had known birth defects, but we were under the care of a doctor (many in fact, even maternal-fetal specialists).
A couple days later, Grand View Ultrasound called us back to cancel our appointment, saying the ultrasound technician wasn't "comfortable" doing the ultrasound. I was so floored, I just said okay and hung up the phone.
Since we were prepared to have our doctor complete the Physician Notification Form, there was no reason to refuse us.