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Lumbar puncture

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This page tells you about a test called a lumbar puncture. You can read about

 

A quick guide to what’s on this page

What is a lumbar puncture?

A lumbar puncture is a test to check the fluid that circulates round the brain and spinal cord (the cerebrospinal fluid or CSF). It can check for cancer cells or for infection in the CSF.

Having a lumbar puncture

You can have a lumbar puncture as an outpatient. There is no special preparation. You wear a gown. You usually lie on your side and bring your knees up slightly towards your chest so that your rounded back is towards the doctor. Sometimes people have the test sitting up and leaning forward. 

To prevent infection your doctor will wear gloves and put some sterile covers over you. The doctor injects a local anaesthetic to numb the area on your back. Then they push a needle very carefully into the small of your back. The needle goes into the space around the spinal cord. It takes a few seconds for a few drops of fluid to drip from the needle into a sterile pot. The doctor takes the needle out. Then they send the sample to the laboratory where a pathologist examines the fluid under a microscope.

A lumbar puncture can be uncomfortable but is not usually painful. You may feel some pressure when the needle first goes in. After the test you need to lie flat for a couple of hours to prevent a headache.

The results

If you have the test as an emergency you may get the results within a couple of hours. Generally, it can take up to a couple of weeks.

 

CR PDF Icon You can view and print the quick guide for this page About the lumbar puncture test.

 

 

What a lumbar puncture is

A lumbar puncture is a test to check the fluid that circulates round the brain and spinal cord (the cerebrospinal fluid or CSF). For cancer, this test is usually done to see if there are any cancer cells in the fluid. But it is also used to look for infection.

 

Having a lumbar puncture

Your doctor will put a needle into the area between your spinal bones and collect some of the fluid that drains out. You will usually be asked to lie on your side and curl up slightly so that your back rounds towards the doctor, who will be behind you. Or you may sit leaning forward. It is important to keep as still as you can, so make sure you are reasonably comfortable before the doctor starts.

You may have to change into a gown first. The doctor will put on gloves and drape some sterile cloths over you before they start. This helps to stop any infection from getting into your spinal fluid. The doctor will inject a little local anaesthetic to numb the area. Once the anaesthetic has worked, they will push the needle very carefully into the small of your back. The needle goes into the space around the spinal cord. Once it is in the right place, it only takes a couple of seconds for a few drops of fluid to drip out into a sterile pot. Then the doctor takes the needle out. The fluid is sent to the laboratory and examined under the microscope for cancer cells. The diagram below shows how you lie and where the doctor puts the needle.

Lumbar puncture

Lumbar puncture - showing where the doctor puts the needle

A lumbar puncture can be uncomfortable, but is not usually painful because of the local anaesthetic. You may feel some pressure and a slight soreness when the needle first goes in. Most children will have some type of sedative before the test so that they are sleepy and can lie still. 

 

After a lumbar puncture

After a lumbar puncture, you can usually go home the same day. But your doctor will probably ask you to lie flat for a few hours after the test. This helps to prevent a headache afterwards. You may still get a headache after this test, so make sure you have some painkillers at home, just in case.

 

Your results

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. The sample of spinal fluid goes straight to the medical laboratory. There, a pathologist examines it under a microscope and does tests. What exactly is done will depend on why you are having the lumbar puncture. When all the tests are done, the pathologist dictates a report. The typed up report then goes to your specialist, who gives the results to you.

Understandably, waiting for results can make you anxious. If your doctor needed the results urgently, they will put that on the request form and so the results may be ready the same day. Try to remember to ask your doctor how long you should expect to wait for the results when you are first asked to go for the test. If it is not an emergency, and you have not heard a couple of weeks after your test, you could ring your doctor's secretary to check if they are back.

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Updated: 21 August 2013