A lumbar puncture is done to take a sample of the fluid that surrounds the brain and spinal cord. The fluid is called cerebrospinal fluid (CSF). The sample will be examined under a microscope in a laboratory.
A lumbar puncture is sometimes used to check for cancer cells in the CSF. This can help to diagnose some cancers, or give more information about the cancer.
A lumbar puncture can also be used to:
- measure the pressure of the CSF
- inject treatment into the CSF, such as chemotherapy (intrathecal chemotherapy) or painkillers
- check for an infection in the CSF.
Your cancer doctor or specialist nurse can tell you if you might need a lumbar puncture.
A lumbar puncture is carried out by a doctor or specialist nurse. It can be done in the outpatients department or on a ward at the hospital. Before you have the test, tell your doctor if you are taking any medicines to thin your blood.
Lumbar punctures are usually carried out under local anaesthetic.
To take the sample of CSF, a hollow needle is inserted between the bones of the lower back and into the fluid around the lower part of the spinal cord. A few drops of the fluid are then collected.
A lumbar puncture can be done while you are lying on your side or sat upright and leaning forward. You may be asked to lie on your side with your knees pulled up towards your chest and your chin tucked in.
Or you could be asked to sit up, bent forwards over a table and supported on pillows. The person doing the lumbar puncture will explain further.
Having a lumbar puncture should not be painful. The local anaesthetic may sting slightly and you may feel pressure as the needle is put in.
After removing the sample of CSF, the needle will be removed. A plaster or small dressing will be placed over the area. The dressing can usually be removed the next day.
You will be asked to lie flat for at least half an hour after the lumbar puncture. Your doctor or nurse will tell you how long. You will normally have your blood pressure and pulse checked during this time.
Once you have rested and feel well, you can get up and go home. You will need someone to collect you from the hospital, as you should not drive for 24 hours. It is also recommended that you take things easy for the first 24 hours after a lumbar puncture is done.
A lumbar puncture is usually a very safe procedure. Some people may have a headache for a few days. If this happens, let your doctor or nurse know so that they can prescribe painkillers for you. Drinking plenty of fluids (3 litres a day) for the next 2 days can help reduce headaches.
Occasionally the headache can be severe and last for a few days. This is usually because of low pressure in the fluid around the brain. You may feel very well when lying flat but as soon as you try to stand up the headache becomes very bad. Contact your cancer doctor or specialist nurse if this happens. Try to rest as much as you can and drink plenty.
You may get swelling or bruising and lower back pain in the area where the needle was put in. This will get better on its own in a few days. Tell your doctor if it continues or gets worse.