FNAC Test (Fine Needle Aspiration Cytology): Why and How is it Done?

Fine needle aspiration cytology, abbreviated as FNAC, is a minimally invasive, quick, and effective biopsy test. It specializes in identifying the prevalence of neoplasms, tumors, and tumor-like lesions in various organs and other parts of the body. These organs and body parts include thyroid nodes, lymph nodes, breasts, kidneys, lungs, liver, salivary glands, prostate, salivary glands, pancreas, retroperitoneum, and many others.

This type of biopsy is often recommended along with computed tomography (CT) or ultrasound. It helps in confirming that the needle is being inserted at the accurate site.

Why is it done?

Let’s take a closer look at the purpose of the fine needle aspiration cytology test:

• It evaluates the presence of lumps and tumorous growths in various organs and other parts of the body like the skin of the neck, armpits, groin, etc.
• It diagnoses both benign and malignant cancers in deep-seated areas or organs that cannot be accessed with invasive surgical procedures. 
• Differentiates between malignant (metastasizing, spreading cancers) and non-malignant (localised and harmless) cancers.
• Tracks the metastasis or progression of cancers as per stages I to IV. 
• Offers a closer study of fluid-filled cysts that have been felt during physical examination or have become evident through X-ray and/or CT and MRI scans.
• The biopsy test analyzes the risk of recurrence of cancer after treatments like radiotherapy, chemotherapy, and cancer surgery.
• It determines the efficacy of the treatment for tumour growth that has already been diagnosed.

Prerequisites

There is no special preparation that has to be done before undergoing this test unless your doctor has recommended otherwise. There are some tests that require patients to fast and an avid food and/or water for a few hours before taking the tests. The period of fasting also varies between tests. However, in most cases, the FNAC test does not generally require patients to fast. It is best to discuss this with your doctor and confirm the same. 

You also need to clarify with your doctor whether you can continue taking the medications, if any. This is because there are certain drug components that adversely affect the accuracy of the test results. Your doctor will analyse whether the medications you are presently taking or have taken in the recent past are amongst those that may interact with this diagnostic test.

You will be advised to temporarily stop taking the medication for a few days before and/or after taking the biopsy test. These medications include non-prescription or OTC (over-the-counter) drugs, prescription-based drugs, herbals, vitamins, and supplements.

Understanding the FNAC test results

At the laboratory, a pathologist observes the collected tissue, cell, or fluid under a microscope. The fine needle aspiration cytology test accurately diagnoses the exact location of tumors or lesions.

It also detects the extent of the abnormalities and the disorder that is the underlying cause of the symptoms. The course of treatment is decided by your doctor based on the results of the FNAC test. There is a risk of the test generating a false negative result.

When should it be repeated?

In case your doctor suspects a false negative result, he/she may advise you to do a repeat fine-needle aspiration cytology test.

If there is a recurrence of a tumor, cyst, or growth that needs to be studied, your doctor may advise you to repeat the test as appropriate. A repeat test will also be done if you are under treatment and the condition reappears.

Procedure for the FNAC Test

A narrow-gauge needle, which is attached to a syringe, is inserted into the area or organ which is to be biopsied. The purpose of this process is to remove a small part of the lesion in the organ as a sample.

The medical expert performing the biopsy test sucks cells, tissues, or fluid from the relevant area or organ and collects it in the syringe that is attached to the needle. This sample is sent to a laboratory for microscopic evaluation.

The pain of this minimally invasive aspiration cytology test varies between patients. Some patients may experience mild pain and/or inflammation at the surgical site until after a few days of the biopsy test. Your doctor may advise a pain reliever like paracetamol to soothe the temporary discomfort and heal the puncture wound. Follow the doctor’s advice.