What is fine needle aspiration cytology (FNAC)?
By Dr Rishu Agarwal, MD (Pathology)
Fine needle aspiration cytology (FNAC) is a diagnostic procedure where a needle is inserted into your body, and a small amount of tissue is sucked out for examination under a microscope. Fine needle aspirations are often performed when a suspicious lump is found, for example a breast lump or enlarged lymph node, or if an abnormality is detected on an imaging test such as x-ray, ultrasound or mammography. Fine needle aspiration is a relatively non-invasive, less painful and quicker method when compared to other methods of tissue sampling such as surgical biopsy.
Fine needle aspiration cytology (FNAC) is ordered by your health care provider when a lump is discovered during examination or during sonography, and your physician wants to determine what the nature of the lump is. In the past, the only way to do this was to have you go to the hospital and undergo a surgical procedure that may be painful, might cause scarring, had more complications, and involved a longer period of anxiety while waiting for the results.
With the use of FNAC, all this is unnecessary in most cases. We can now sample your lump using only a thin small needle which will leave a mark no bigger than a needle stick from a blood test. Furthermore, this test will most often allow us to make a diagnosis of your lump within 3 to 4 days of the test. Fine needle aspirations may be performed on palpable lumps (lumps which can be felt), or impalpable lumps which have been detected on ultrasound or x-ray.
Once the skin has been cleaned at the needle entry point, the lump is then examined. If the lump can be felt, your doctor or surgeon will palpate the lump to position it for the needle. If the lump cannot be felt, imaging may be required to find the exact location. This can be done with ultrasound, where the surgeon will watch the needle on the ultrasound monitor and guide it to the area, or with a stereotactic mammogram (for the breast) which uses two mammograms at different angles and a computer to create exact coordinates. The type of needle used for fine needle aspiration biopsy has a hollow interior and is much finer than a regular needle used to draw blood.
How is FNAC performed?
First the doctor will ask you some questions about the lump: where it is, how and when you first became aware of it, and if you’ve noticed any changes in it. Next, the doctor will feel the lump. Before the actual biopsy is performed the doctor will give you an opportunity to ask any questions or express any concerns you might have about the procedure.
After all your questions and concerns have been addressed, the actual procedure will begin. Holding the lump with one hand, the doctor will precisely sample the lump with a thin needle held in a needle holder, which provides greater control. Usually, 2 to 3 samples will be required from the lump to provide an accurate diagnosis. The lump or mass to be aspirated is fixed between the fingers. The needle is gently pricked into the lump and more slowly in different direction and this procedure should not be performed for more than 20-40 seconds. The needle is taken out before blood is seen in it.
How long will it take?
Each sample will only take about 10 seconds to obtain. The whole procedure from start to finish usually takes no more than 10 to 15 minutes. However, please allow an hour for your visit because of registration and possible waiting time in the office.
When are the results available?
Generally, your results should be available in 3 to 4 working days. The results can be grouped into 3 categories:
clearly benign (not cancer)
clearly malignant (cancer)
non-definitive, less clear (most often, this will be followed by a surgical biopsy)
- No anaesthesia is required.
- No hospitalization is required.
- It is easy to perform and is least invasive.
- It is economical.
- Cysts can be aspirated easily and diagnosed with this procedure.
- It has better patient compliance.
- The results are extremely satisfactory in good hands.
- The exact cytological diagnosis is available before definitive surgery is planned.
- It is a cost effective procedure.
- It can relieve the anxiety and uncertainty in both patient and physician by making an accurate diagnosis pre-operatively.
How reliable is FNAC?
In the hands of a skilled FNAC practitioner, this test is very reliable. In the instance of a clearly benign diagnosis, it may prevent you from undergoing surgery.
In the case of a clearly malignant diagnosis, it quickly establishes the need for further treatment. In the less frequent occurrence of a non-definitive diagnosis, either repetition of the FNA or a surgical biopsy is usually recommended.
Fine needle aspiration biopsy, when carried out by an experienced practitioner is virtually free of significant complications.
The most common complication is a slight bruising or tenderness of the area for a few days following the procedure. Discomfort should be relieved by an over-the-counter pain reliever or the application of an ice-pack for short periods following your return home.
A fine needle biopsy is an effective tool in evaluating and diagnosing suspect lumps or masses. A quick diagnosis can mean that cancer is detected early, giving more options for treatment, or that benign lumps are diagnosed without the need for surgery.
It is non-invasive and only slightly uncomfortable, compared to a surgical biopsy which requires a general anesthetic, involves pain and the possibility of infection or scarring. Fine needle aspiration biopsies do require some expertise to perform and interpret.
To ensure that an accurate result is achieved, it is important that the general practitioner, radiologist, surgeon, pathologist or oncologist who performs your procedure has experience in fine needle aspiration biopsy.