We do this using instruments we call a cannula. This is a hollow metal tube that can range in diameter from 1 to 5 millimeters. On the end there are a variety of shapes and hole patterns thru which the fat is suctioned.
The operation carries out something like this. The patient is anesthetized and positioned so the area of interest is exposed. The skin is sterilized and then small, and small means 2 or 3 mm, skin nicks are made. The cannula is slipped into the fatty tissue thru the skin nick and a back and forth motion is made like you are shooting pool. The cannula is attached to tubing that connects to a suction machine and the fat is removed. Most cases can be completed in an hour or two and almost all are done as an outpatient.