Second opinion

A second opinion was an analysis given by a doctor other than the patient's current doctor, by reviewing their medical records and providing an opinion on the diagnosis, prognosis, and recommended treatments.

In 2365, Data told Guinan a joke ("A guy walks into the doctor's office. The doctor tells him you need an operation. The guy says I want a second opinion. The doctor said, okay, you're ugly too."), but it wasn't funny the way he said it. (TNG: "The Outrageous Okona")