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Lumbar puncture

A lumbar puncture is a test to check the fluid that circulates around the brain and spinal cord. This is called the cerebrospinal fluid or CSF.

Why you have a lumbar puncture

Certain types of brain tumours can spread from the brain to the CSF. So doctors might take some of the CSF to test for tumour cells. They use a needle to take a sample of the CSF from your lower back.

Sometimes, the pressure inside the brain and spinal canal (the intracranial pressure) is too high. It might not be safe to do a lumbar puncture if this happens. 
 

Diagram showing how you have a lumbar puncture

You normally have this test in the outpatient department under local anaesthetic. This means you are awake but the area is numb. 

Preparing for your lumbar puncture

Check your appointment letter for how to prepare for your lumbar puncture test. You are usually able to eat and drink before your test. Take your medications as normal. 

Children and some adults may have this under a general anaesthetic (GA) or with sedation. You have to stop eating and drinking for some time before the test if you're having a GA. 

What happens

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

When you arrive at the clinic a staff member asks you to take off your upper clothing and put on a hospital gown.

You usually lie on your side with your knees tucked up into your chest. It's important to stay as still as you can during the test, so make sure you are comfortable before it starts.

The doctor or nurse drapes some sterile covers over you. Then they clean the area with antiseptic fluid, which can feel cold.

You have an injection of anaesthetic into the area. When the area is numb, the doctor or nurse puts the lumbar puncture needle in through the skin. It goes into the small of your back and into the space around the spinal cord. You might feel some pressure when the needle goes in.

Once it's in the right place, the fluid drips out into a pot. This only takes a few seconds.

Your doctor or nurse takes the needle out and puts a dressing or plaster on your back.

The whole test takes 20 to 30 minutes. It can be uncomfortable but it's not usually painful.

After your lumbar puncture

You lie flat for an hour or so after the test.

Tell your doctor or nurse if you have a headache, so they can give you some pain killers. Lying flat and drinking plenty of fluids may relieve your headache. This may last for a couple of days so make sure you have pain killers to take home. 

You will have a dressing on the skin where they did the test. 

You can usually go home the same day. 

Possible risks

A lumbar puncture 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 lumbar puncture outweigh these possible risks.

Headache

If your headache doesn't get better contact your hospital team.

Pain

You might have lower back pain for a couple of days after the test. Contact your hospital team if the pain is severe.

Bleeding

This is very rare. Contact your hospital team if you have bleeding for more than 15 minutes.

Infection

This is very rare. Contact the hospital straight away if you:

  • have a high temperature
  • are being sick
  • are sensitive to bright light
  • have tingling or numbness in your legs
  • have a severe headache

Getting your results

You should get your results within 1 or 2 weeks. 

Waiting for results can make you anxious. Ask your doctor or nurse how long it will take to get them. Contact the doctor who arranged the test if you haven’t heard anything after a couple of weeks.

You might have contact details for a specialist nurse who you can contact for information if you need to. It may help to talk to a close friend or relative about how you feel.

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

More information

We have more information on tests, treatment and support if you have been diagnosed with a brain or spinal cord tumour.

Last reviewed: 
27 Mar 2019
  • Brain tumours (primary) and brain metastases in adults
    The National Institute for Health and Care Excellence (NICE), July 2018

  • The Royal Marsden Manual of Clinical Nursing Procedures (9th Edition)
    L Dougherty and S Lister (Editors)
    Wiley-Blackwell, 2015

  • Body position and intake of fluids for preventing headache after a lumbar puncture 
    I Arevalo-Rodriguez and others
    Cochrane Database of Systematic Reviews 2016, Issue 3

  • Oxford handbook of clinical medicine (10th edition)
    M Longmore and others
    Oxford University Press, 2017

  • Overview of the clinical features and diagnosis of brain tumors in adults
    E Wong and J Wu 
    UpToDate, Last accessed March 2019

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