A lumbar puncture (spinal tap) is done to test the fluid (cerebrospinal fluid or CSF) around the spinal cord and brain. By placing a thin hollow needle between the bones of the lower back, a small sample of fluid can be taken for testing.

A lumbar puncture can detect:

  • Infection 

  • Inflammation 

  • Cancer

  • Bleeding

The Procedure

We will ask you to lie on your side with your knees drawn up and your head bent down. We also may ask you to sit, leaning over a table. You must remain as still as you can during the procedure. We will give you a shot to numb the puncture site. You will feel pressure as the doctor inserts the needle. Let the doctor or nurse know if you feel any pain. Breathe deeply and slowly. The CSF will come out through the catheter drop by drop. Once we have taken enough fluid for testing, we will pull the needle out. We may place a bandage over the site. The entire test will last about 20 to 30 minutes.


Some of the risks include:

  • Pain – Patients may feel a poke as the doctor inserts the needle into the back. We use medicine to numb or lessen the pain. Once the needle is in, the pain is often mild and goes away. If you feel pain into one buttock or down one leg please let the person doing the procedure know. 

  • Headache – You may have a headache after the test. It will depend on your position. It will happen when sitting or standing and resolve when laying down. This will go away on its own but please let your nurse know if your headache is bad.

  • Bleeding – When the doctor inserts the needle, there is a risk of bleeding at the site. If this happens, the bleeding is often light or stops on its own. Bleeding into the spinal canal is rare.