FINE NEEDLE ASPIRATION

Sometimes enlarged lymph nodes, abnormal body organs or an abnormal mass lesions are identified during imaging and fine needle aspirate (FNA) are recommended to obtain cellular samples.

The patient is sedated or under anaesthesia, depending on the location of the abnormality.

A small needle is guided into place using ultrasound and samples obtained.

As the needle size is very small, the sample obtained is also very small and there are some diseases that can be difficult to diagnose using this method. Some diseases though such as lymphoma or certain types of infections can be easily diagnosed this way.

Results are typically obtained within 48 hours of submission of the sample to the laboratory.

QUESTIONS AND ANSWERS

What is a fine needle aspirate?

Fine needle aspiration is a type of biopsy procedure. During the procedure, a small needle is inserted into the region of concern and a sample is collected onto a microscope or slide or sterile container. These samples can help make a diagnosis e.g. of infection or cancer.

When is a fine needle aspirate used?

A fine needle aspiration is most commonly performed on a lump or abnormal appearing organ. These changes maybe identified on physical examination or on an imaging test such as an ultrasound or CT scan.
Fine needle aspiration may also be performed on:
- cysts (fluid-filled lumps)
- nodules or masses (solid lumps)
- enlarged lymph nodes
Without a biopsy, it's difficult for a veterinarian to know what these abnormal areas contain.

How is a fine needle aspiration performed?

Your cat is likely to be under sedation or anaesthesia for this process. This is not because it is painful but to keep them still during the procedure.
Their fur is clipped and the area is cleaned.
We will sometimes use a local anaesthetic on the skin.
Ultrasound can be used to help locate the region for fine needle aspiration.
A thin needle is attached to a syringe and inserted through the skin into the abnormal area.
A sample is suctioned (aspirated) into the needle and syringe and then placed on a microscope slide and/or sample pot.
Several needle insertions may be required to ensure that the sample is adequate.

How long does a fine needle aspirate take?

The fine needle aspiration itself is usually a short procedure, less than 10 minutes-20 minutes depending on how many samples are required

What should I expect with my cat after their fine needle aspirate?

If your cat has been sedated they may be a little groggy afterwards but this should only last for a few hours.
Rarely there may be a little bruising at the site.

What complication can occur with fine needle aspirates?

Serious complications after fine needle aspiration are rare.
Minor bleeding under the skin at the biopsy site can occur.
Sometimes bleeding can occur from tumours or tissues with blood vessels.

How reliable are the aspirate results?

A fine needle aspirate is an effective tool in evaluating and diagnosing suspect lumps or masses. It is minimally invasive, however compared to a surgical or trucut biopsy samples are very small and fine needle aspiration biopsies do require some expertise to perform and interpret.
Because an FNA biopsy can only sample a small number of cells from a mass or lump, there is a risk that any abnormal cells may be missed and not detected.

What happens to the sample?

The samples are either assessed in the hospital or sent to a laboratory. The material is examined used the microscope after it has been prepared and stained so that the cellular material can be examined.

How long does it takes to get results?

Results are received within 24-48 hours and we will contact you as soon as we have received them.

The needle is inserted through the skin into the area of interest and a sample obtained.

The sample is placed onto microscope slides and examined under the microscope after special staining techniques are used.

This is an example of a slide from a cat with lymphoma. The big round purple cells are the cancerous lymphocytes.

Your cat is monitored closely during and after the procedure.