A small needle is inserted into the lump to remove cells that are then examined under the microscope to make a diagnosis. Multiple sticks with the needle may be performed to get enough cells. If the lump is difficult to feel, an ultrasound device can be used to help direct the needle into the lump.
Local anesthesia (numbing medicine) may be injected into the skin over the area where the biopsy will be performed. Although not painless, the discomfort from FNA is usually minimal and can be treated with ice or Tylenol® if needed. Most often, the needle used for FNA is smaller than a needle used for a blood test from the arm (venipuncture).
Although no test is perfect, FNA is generally accurate and can often be used instead of an open surgical biopsy, which is usually more painful, costly, and may require the patient to be asleep.
Typically, the results from an FNA are available after a few days. These results may indicate a cancerous (malignant), noncancerous (benign), or indeterminate (uncertain) diagnosis. If the diagnosis is uncertain, your doctor will talk to you about whether another FNA or different type of procedure may be needed.