A lumbar puncture (also called a spinal tap) is a common medical test that involves taking a small sample of cerebrospinal fluid (CSF) for examination. CSF is a clear, colorless liquid that delivers nutrients and "cushions" the brain and spinal cord, or central nervous system. In a lumbar puncture, a needle is carefully inserted into the lower spine to collect the CSF sample.
Frequently Asked Questions
What should I expect?
- While the lumbar puncture is being done, you will need either 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 positioning allows your back to curve as much as possible so that the bones of the spine (vertebrae) are widely separated.
- The area of skin over the lower spine is cleaned with an antiseptic solution. Local anaesthetic is injected to numb the area. The radiologist will wait for a few minutes for the anaesthetic to take effect.
- A hollow needle is inserted between two of the spinal bones and into the spinal canal. You will need to stay as still as possible at this time. You may feel a sensation of pressure as the needle is inserted. Samples of CSF may then be withdrawn and/or chemotherapy drugs may be inserted.
- If chemotherapy drugs are being given, the doctor and nurses will do a number of safety checks to ensure you are given only the medicines that have been prescribed for you. This is because only certain drugs can be given in this way. If you would like to, you can also check the drugs before they are given.
- After the lumbar puncture has been completed, the needle is removed and a small dressing is put on. The entire procedure normally takes around 20 minutes, although this can vary depending on the reasons for why it is being done.
- Lumbar puncture is not usually painful, although some people may find it uncomfortable. Some people may have a headache for a few hours afterwards. You will need to lie flat for a while after the procedure – from one hour to several hours, depending on how you feel. You will be able to roll from side to side, but if you have a headache, sitting up can make it worse.
- Let the doctor or nurse know if you have a headache, as mild painkillers can be given to help. You will also have your blood pressure and pulse checked again during this time. Ask the doctor or nurse when it will be safe for you to sit up. Once you have rested and feel well, you can safely return to your normal activities, although it is best not to drive or operate machinery for 24 hours after a lumbar puncture.
- Sometimes a lumbar puncture is done more than once. Often, several doses (cycles) of chemotherapy are needed, and a lumbar puncture will be done during every cycle until all of the planned treatment is completed.
How will I find out the results?
After the procedure, your physician will receive a copy of your results to discuss with you.