The most common type of mastectomy is a modified radical mastectomy,
in which the entire breast and some or all of the lymph nodes under your arm are removed.
In this procedure, your surgeon will make an incision along the length of your breast,
separate your breast tissue from the muscle underneath, and remove it for examination.
To remove the lymph nodes under your arm, many surgeons use a technique called sentinel node biopsy.
In this procedure, dye is injected into your breast to determine which lymph nodes drain fluid first.
It is these lymph nodes that are most likely to contain cancer.
Your surgeon will remove one to three of these lymph nodes for examination,
insert drains, and close the wound with sutures.