Fine needle aspiration of lymph nodes for anal cancer

A fine-needle aspiration is a way of taking a sample of cells.

Your doctor examines your groin for swollen (enlarged) lymph nodes. Your groin is the area at the top of your legs. You might also have an ultrasound scan to check the nodes. Ultrasound scans use high-frequency sound waves to create a picture of a part of the body.

If any lymph nodes look or feel abnormal, your doctor will take a sample (biopsy) using a needle and syringe to check for cancer cells. This is called a fine needle aspiration (FNA).

What is a lymph node?

A lymph node is part of the lymphatic system. This is a network of thin tubes (vessels) and nodes that carry a clear fluid called lymph around the body. This is an important part of the immune system. It plays a role in fighting infection and destroying old or abnormal cells.

The nodes are bean shaped structures that filter the lymph fluid and trap bacteria and viruses, and cancer cells.

Diagram of the lymphatic system

Why you might have a fine needle aspiration

A fine-needle aspiration helps your doctor to check if there are any cancer cells in the lymph nodes in your groin. This way, they know if your cancer has spread to the lymph nodes. It also helps them decide on what treatment you should have.

Preparing for your fine needle aspiration

You are able to eat and drink normally before an FNA. Take your medicines as normal. But if you are taking any blood thinning medicines you might need to stop them before the test. Your doctor or nurse tells you when to stop.

Your doctor or nurse give you information about the procedure and ask you to sign a consent form. This is a good time to ask any questions that you have.

What happens?

You will have the test lying down on the couch.

Your doctor cleans your skin and then numbs the area with local anaesthetic. They put a fine needle through your skin and draw back some cells and fluid into a syringe. They might use an ultrasound to help guide the needle into the lymph node.

They then send the sample to the lab where a specialist doctor (pathologist) looks at it under a microscope.

After your fine needle aspiration

You can get dressed and go home or back to work straight afterwards if you like. But try not to do too much for the rest of the day. 

Possible risks

A fine needle aspiration is a very safe procedure, but your nurse will tell you who to contact if you have any problems after your test. Your doctors will make sure the benefits of having a fine needle aspiration outweigh these possible risks.


It’s rare to have any bleeding after your fine needle aspiration. Your doctor or nurse will give you advice on what to do if you have any bleeding.


Some people have swelling afterwards, but this is rare. Let your doctor know if the area is swollen or very painful.

Getting your results

You should get your results within 1 or 2 weeks at a follow up appointment. 

Waiting for test results can be a very worrying time. You might have contact details for a specialist nurse who you can contact for information if you need to. It can help to talk to a close friend or relative about how you feel.

You can also contact the Cancer Research UK nurses on freephone 0808 800 4040 for information and support. The lines are open from 9am to 5pm, Monday to Friday.

Contact the doctor who arranged the test if you haven’t heard anything after a couple of weeks.

You will need to have your lymph nodes removed in an operation called a lymph node dissection if they contain cancer cells.

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