Lumbar puncture

A doctor or specialist nurse may do a lumbar puncture. This means they take a sample of the fluid that surrounds the brain and spinal cord. This fluid is called cerebrospinal fluid (CSF). They take it from the lower back. The sample is then checked under a microscope.

A lumbar puncture can be used to:

• check for cancer cells in the CSF – to diagnose some cancers or give more information about a cancer
• measure the pressure of the CSF – to help diagnose certain conditions
• check for infection in the CSF
• inject treatment into the CSF, such as painkillers or chemotherapy (intrathecal chemotherapy).

After collecting the sample of CSF, the doctor or nurse removes the needle. They put a plaster or small dressing over the area. The dressing can be removed after 24 hours.

You need to lie flat for at least 30 minutes after the lumbar puncture. Your doctor or nurse will tell you how long you should stay like this. They will check your blood pressure and pulse during this time.

Once you have rested and feel well, you can get up and go home. You should not drive for 24 hours. You will need to ask someone to take you home. Try to avoid doing too much for the first 24 hours after the lumbar puncture.

A lumbar puncture is usually a very safe procedure. But you may have a headache for a few days. If this happens, tell your doctor. They can give you painkillers to help. Drinking plenty of fluids (3 litres a day) for 2 days afterwards can help to reduce headaches.

Occasionally, the headaches may be severe. This is usually because of low pressure in the fluid around the brain. You may feel fine when lying flat. But when you try to stand up, the headache may get very bad. Contact your cancer doctor or specialist nurse if this happens. Try to rest as much as you can and drink plenty of fluids.

You may get swelling, bruising or pain where the needle went in. These symptoms will get better after a few days. Tell your doctor if they continue or get worse.