A fine needle aspiration biopsy can be done in several different ways:
Fine-needle aspiration (FNA) for palpable growths: A palpable growth is one that can be felt. The patient usually sits up while the doctor inserts a small hollow needle with a syringe to withdraw (aspirate) fluid and cells from the growth for testing. The doctor simply feels (palpates) the suspicious area to the needle to the site. When the needle reaches the mass, the doctor suctions out a sample with the syringe. The doctor repeats this procedure several times. If the mass is a cyst, the withdrawn samples will consist mainly of fluid and the cyst may collapse, relieving any pain the patient feels. If the mass is solid, the samples will consist primarily of tissue cells.
By analyzing the samples immediately after their withdrawal, a doctor may be able to determine that they came from a cyst and simply discard them, diagnosing the growth as benign. In all other cases, fluid and tissue samples are placed on slides and then analyzed by a pathologist in a laboratory. Atypical cells found in a fine-needle aspiration biopsy may signal that cancer is present or that repeat biopsies are necessary.
Guided FNA for non-palpable growths: When a growth is too small or deep to palpate (feel), the doctor must locate it with one of several imaging techniques. First, the patient lies face-down on a table with the breasts suspended through an opening. With stereotactic mammography, mammograms of the suspicious breast site are taken from different angles to form a virtual three-dimensional (stereotactic) image that precisely pinpoints the location of the suspicious area. The computer then uses a motor to guide a small hollow needle to the site to remove the samples. The withdrawn samples are then analyzed for the presence of cancer. Ultrasound and MRI are other imaging techniques that may be used to guide breast biopsies.