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HealthInfo Waitaha Canterbury

Lumbar puncture

Werohanga tangai

In a lumbar puncture, a hollow needle is inserted between the bones of your lower back into the fluid around the lower part of your spinal cord. A sample of fluid is drawn off and sent to the laboratory for testing. This fluid is called cerebrospinal fluid (CSF).

Lumbar punctures are done for two main reasons: to make a diagnosis or to inject drugs such as antibiotics, chemotherapy or pain medication into your CSF. They can also be done to measure the pressure in your CSF or to drain CSF if the pressure is too high.

Your lumbar puncture will be carried out by a doctor, who will explain what happens and why you need one. It will take around 20 minutes.

Injecting chemotherapy into the CSF is known as intrathecal chemotherapy. This can be done for people whose cancer has spread into their CSF or to help stop this from happening.

During a lumbar puncture

It may help if you go to the toilet before you have your lumbar puncture, as you'll need to lie flat for some time afterwards.

During the lumbar puncture, you'll either be asked to lie on one side with your knees drawn up towards your chest or to sit up bent over a table and supported by pillows. This helps your back to curve as much as possible, so the bones of your spine (your vertebrae) are widely separated.

The skin over your lower spine will be cleaned and a local anaesthetic will be injected to numb the area.

The doctor will insert a hollow needle between two of your vertebrae into your spinal canal (the space in the middle of your spine, where your nerves are). You'll need to stay as still as possible. You may feel some pressure as the needle is put in. The doctor will take samples of your CSF or inject chemotherapy drugs if that is what you need. They will then take the needle out and put a small dressing over the site.

After a lumbar puncture

A lumbar puncture is not usually painful, although some people may find it uncomfortable. You may have a headache for a few hours afterwards and will need to lie flat for an hour. You'll be able to roll from side to side but sitting up can make a headache worse. The headache might continue for up to three days.

Let the doctor or nurse know if you have a headache, as they can give you mild pain relief such as paracetamol. Your blood pressure and pulse will also be checked. Ask the doctor or nurse when it will be OK for you to sit up. Once you have rested and feel well, you can return to your normal activities.

Sometimes people need more than one lumbar puncture. If you're having intrathecal chemotherapy, you may need several doses and will need to have a lumbar puncture each time.


The most frequent complication is a headache. If you have a lasting headache, please contact the department or ward where you had your lumbar puncture.

You may bleed slightly from the lumbar puncture site, but this is usually minor.

There is a small risk that the lumbar puncture site will become infected. If you're feeling unwell, have a fever or any other concerns related to your lumbar puncture please contact the department or ward where you had your lumbar puncture.

Getting help

If your lumbar puncture was done by the Haematology team, phone the Haematology ward on (03) 364-0384 any time.

Written by the Canterbury Regional Cancer and Haematology Service. Adapted by HealthInfo clinical advisers. Last reviewed February 2023.


Page reference: 32097

Review key: HILUP-32097