Fine Needle Aspiration (FNA)

J. Taylor Whaley, M.D.
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: December 29, 2014

What is a fine needle aspiration?

  • A FNA is a simple biopsy procedure, generally performed to learn more about a lesion, or abnormality, seen on a radiology test or discovered on a physical exam. The various scans, including CT scans, MRI scans, and ultrasounds, have become very good at finding abnormal things within the body; however, it is often impossible using scans to know if the abnormality is benign (not cancer) or malignant (cancer). It is very important to remember that just because something is abnormal, it does not mean it is something bad or dangerous. The majority of abnormalities seen on CT or MRI scans turn out to be benign findings.
  • FNA can be used for almost any part of the body. Common locations include the thyroid, lymph nodes in the neck or other areas of the body, lung lesions, liver abnormalities and pancreas masses. FNA is occasionally used to evaluate a breast mass, though more often these are evaluated using core needle or excisional biopsies.
  • There are several different types of biopsies that can be used to assess a mass or lesion. In this article, FNA will be discussed; however, please refer to Core Needle Biopsy and Incisional & Excisional Biopsy for more details on those types of biopsies.
  • An FNA is minimally invasive, well tolerated and quick.

How is this test performed?

  • FNAs are performed as an outpatient procedure. Major anesthesia is not needed because it is so well tolerated. In many cases, a local anesthesia, such as lidocaine, will be used to numb the area.
  • During an FNA, a very thin needle (even smaller than the needle used to draw blood) is passed through the mass or lesion of interest.
  • If the mass is not able to be felt (palpated), the radiologist may use an ultrasound, x-ray, or CT scan to help locate the lesion.
  • The needle is generally passed through the lesion several times to make sure enough tissue is obtained.
  • After the biopsy is performed, the sample is placed onto a glass slide so that a pathologist can look at it. A pathologist is a doctor who specializes in looking at tissues under the microscope. After the pathologist has established a diagnosis, a report will be generated for your doctor.
  • The actual insertion of the needle generally only takes 10-15 seconds per insertion. Again, the needle may be inserted several times to obtain enough of a sample. The whole procedure can take 15-30 minutes.
  • The main risk associated with an FNA is bleeding. Generally, there is very little bleeding associated with the procedure. Occasionally, a pocket of blood, or a hematoma, will collect at the site of the biopsy. This can be slightly uncomfortable but should resolve over the next few days. If there is severe pain following the procedure, you should contact your doctor immediately.

How do I prepare for an FNA?

  • Frequently, no preparation is needed; however, if you are on blood thinners, your doctor may ask you to stop them several days in advanced.

How do I interpret the results of a pathology report?

  • Following the biopsy, the tissue sample is processed by a pathologist. A preliminary report may be given to the doctor; however, the final report generally takes several days.
  • The report generally states the patient's name, date of birth, site of biopsy, and indication (reason for the test) at the top of the report. Pathologists report both normal and abnormal findings in a very systematic approach. For this reason, it is very important to discuss the results with your doctor.
    • The first paragraph typically reports the final diagnosis. This is a summary of the findings, often generated to answer the question posed by the ordering physician. If the biopsy is obtained for oncologic purposes, it commonly will state the findings are benign (not cancer), malignant (cancer), or unable to be determined.
    • The following paragraphs generally include the specific technical information involved in obtaining and processing of the sample. The details of the diagnosis can also be found here. Because reports are generated for other medical professionals, the terminology is often medically oriented and can be difficult to interpret.
    • You may want to ask for a copy of the report for your records, but you should ask your healthcare provider to review the results with you.


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