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Lumbar puncture

Find out about having a lumbar puncture including what it is, how you have it and what happens afterwards.

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

Why you might have this test

A lumbar puncture can check for cancer cells or for infection in the CSF.

Doctors remove some of the CSF to test for cancer cells. Using a needle your doctor takes a sample of the CSF from your lower back.

Diagram showing how you have a lumbar puncture

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 anaesthestic (GA). 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 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.


Children might have some type or sedative or general anaesthetic before the test. This is so they can lie still enough for the doctor to take the sample.

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

There is a risk of bleeding and infection but this is very rare.

You should contact your hospital if you get symptoms such as:

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

Your nurse will tell you what symptoms to look out for and who to contact if you have any problems at home.

Getting your results

The fluid is sent to the laboratory and examined under the microscope for cancer cells.

It can take time for test results to come through. How long will depend on why you are having the test. It could be a day or two but can be up to a couple of weeks.

Waiting for results can be an anxious time. It might be helpful to talk to someone close to you. 

If you have not had your results a few weeks after your test, you could contact your doctor to chase your results for you.

More information

We have more information on tests, treatment and support if you have been diagnosed with cancer.

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

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