They were done in breast center clinics that were equipped to do them in the same place that my mammograms, ultrasounds and exams were done. They are able to do needle aspirations, core needle biopsies (what I had), and placement of reflectors that mark the lumps for surgical purposes. Even the day of my surgery I was taken to the breast center to have the reflectors placed as they can't do that in the OR.

Sometimes they'll give you a choice about doing it in the office or a hospital or surgical center if you feel you need more sedation. I had that for a gyn procedure years ago and chose to be put to sleep although I could have done it awake.