Ultrasound scan and fine needle aspiration of the lymph nodes

An ultrasound scan is a procedure that uses high frequency sound waves to create a picture of a part of the inside of your body. A fine needle aspiration is when your doctor uses a thin needle to take a sample of cells from a lymph node.

Your doctor examines your groin Open a glossary itemfor swollen (enlarged) lymph nodes. You might then have an ultrasound scan to check the nodes in your groin. 

After this, you may have a fine needle aspiration to check if there are cancer cells in these lymph nodes.

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.

Parts of the lymphatic system

The lymph nodes are often the first place that a cancer spreads to.

What is an ultrasound scan?

The ultrasound scanner has a microphone that gives off sound waves. The sound waves bounce off the organs inside your body, and the microphone picks them up. The microphone links to a computer that turns the sound waves into a picture on the screen.

Ultrasound scans aren't painful but can cause some discomfort.

What is a fine needle aspiration?

A fine needle aspiration is a way of taking a sample of a lymph node.

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).

Preparing for the test

Check your appointment letter for exactly how to prepare.

You are able to eat and drink normally before an ultrasound scan and fine needle aspiration. 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?

When you arrive at the department, a nurse asks you to change into a gown. Then they show you to the test room.

You'll have the test lying down on the couch. The doctor or a sonographer puts a cold lubricating gel on the skin by the lymph nodes. A sonographer is a trained professional who specialises in ultrasound scanning.

They put a handheld ultrasound probe on your skin. The gel helps the probe to move over your skin. You may feel a little pressure when they move the probe over your skin. Tell them if it is uncomfortable. It shouldn’t hurt.

This will be the end of your test if your lymph nodes look normal. Any changes on the ultrasound need further looking into.

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. Or they take out some tissue through a needle.

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

After your test

You should be able to go home the same day. Try not to do too much for the rest of the day.

You'll have a small dressing over the site. Ask your doctor or nurse how to look after this for the next few days.

Getting your results

It takes 1 or 2 weeks to get the results. Your specialist will usually discuss them with you at your next clinic appointment.

Waiting for test results can be a worrying time. You might have contact details for a specialist nurse. You can get in touch with them for information and support if you need to. It may help to talk to a close friend or relative about how you feel.

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

Possible risks

An ultrasound scan is a very safe procedure. It doesn’t involve radiation and there are usually no side effects.

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.


Contact your GP or the hospital if you have a high temperature or feel unwell. Or if there is redness, swelling or fluid (discharge) at the biopsy site.

Last reviewed: 
07 Dec 2020
Next review due: 
07 Dec 2023
  • Guidelines on Penile Cancer
    OW Hakenberg and others
    European Association of Urology (EAU), 2018

  • Textbook of Penile Cancer

    A Muneer and S Horenblas (editors)

    Springer-Verlag, 2016

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