(Cerebrospinal Fluid Analysis; Cerebrospinal Fluid Tap; Spinal Tap)
by Cynthia M. Johnson, MA
A lumbar puncture is a test of the cerebrospinal fluid (CSF) around your spine and brain. This fluid provides protection and nutrition to the brain and nerve cells. It also helps remove waste products from the brain.
Reasons for Procedure
The test is done to look for anything that is not normal with a person's CSF. It may be done to help diagnose health problems, such as:
It may also be done treat health problems. It can be used to:
Problems are rare, but all procedures have some risk. The doctor will go over some problems that could happen, such as:
What to Expect
Prior to Procedure
A lumbar puncture may be done on short notice. In this case, there are no preparation steps. If it is planned, before the procedure:
Local anesthesia will be used most often. It will numb the area where the needle is inserted.
Description of Procedure
You will likely lie on your side with your knees drawn up in front. Some punctures may be done while you sit on the edge of the bed. The site will be cleaned. A needle will be inserted through the lower back and into the spinal canal. A sample of CSF will be taken through the needle.
The doctor will note the pressure of the CSF. Medicines or dyes may also be injected as part of treatment and diagnosis. The needle will be removed. A bandage will be placed over the site.
Immediately After Procedure
You will lie down for 10 to 60 minutes. You will often be able to go home after the procedure. If you have a severe headache or need immediate treatment, you may need to stay longer.
How Long Will It Take?
About 30 to 45 minutes from setup to completion
Will It Hurt?
The anesthesia will sting when it is injected. The lumbar puncture will cause pressure in the back.
Rest and home care will be needed for at least 24 hours. Medicine will be given to help with any pain.
Call Your Doctor
Call the doctor if you are not getting better or you have:
If you think you have an emergency, call for medical help right away.
Family Doctor—American Academy of Family Physicians
National Institute of Neurological Disorders and Stroke
About Kids Health—The Hospital For Sick Children
Glimåker M, Johansson B, et al. Early lumbar puncture in adult bacterial meningitis--rationale for revised guidelines. Scand J Infect Dis. 2013 Sep;45(9):657-663.
Lumbar puncture (LP). EBSCO DynaMed website. Available at https://www.dynamed.com/procedure/lumbar-puncture-lp . Updated March 27, 2019. Accessed April 9, 2020.
Lumbar puncture. Radiological Society of North America Patient website. Available at: https://www.radiologyinfo.org/en/info.cfm?pg=spinaltap. Updated April 30, 2018. Accessed April 9, 2020.
Last reviewed February 2021 by EBSCO Medical Review Board Rimas Lukas, MD
Last Updated: 4/10/2020
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