A type of surgery used to rebuild the shape of the breast after a mastectomy. A tissue flap, including blood vessels, skin, fat, and sometimes muscle, is removed from one area of the body, such as the back or abdomen. It is then reattached to the chest to form a new breast mound. The blood vessels from the tissue are reconnected to blood vessels under the arm or in the chest. A free flap is a type of breast reconstruction.