Biopsy punches actually come in millimeters and there are two standards sizes, 3mm and 5 mm. Taking a small core with what is essentially a round razor blade is very quick and not painful. They press the little cookie cutter circle against the tissue and it cuts down a few millimeters. They remove the punch and grab the center of the tissue plug with a hemostat, pull on it a little tug, and snip it off with a pair of surgical scissors. Done. A couple of minutes tops. Depending on location they will use a conventional dental anesthetic like lidocaine to numb the area up first. Most are not even stitched up afterwards, or take one stitch only.

Brush biopsies are very unreliable, and do not provide the pathologist with the information that he needs. A punch or incision leaves all the layers of cells intact in their proper relationship ( basal cells on the bottom, upper epithelium cells on top. A brush biopsy gives the pathologist "scrambled eggs" of cells and some of the information is lost.