A lumbar puncture (also called a spinal
tap) is a procedure to collect and look at the fluid (cerebrospinal fluid, or CSF) surrounding the brain and spinal cord.
lumbar puncture, a needle is carefully inserted into the spinal canal low in
the back (lumbar area). Samples of CSF are collected. The samples are studied
for color, blood cell counts, protein, glucose, and other substances. Some of
the sample may be put into a special culture cup to see if any infection, such
as bacteria or
fungi, grows. The pressure of the CSF also is measured
during the procedure.
Why It Is Done
lumbar puncture is done to:
- Find a cause for symptoms possibly caused by an
infection (such as
meningitis), inflammation, cancer, or bleeding in the
area around the brain or spinal cord (such as
certain diseases of the brain and spinal cord, such as
multiple sclerosis or
- Measure the
pressure of cerebrospinal fluid (CSF) in the space surrounding the spinal cord.
If the pressure is high, it may be causing certain symptoms.
A lumbar puncture may also be done to:
anesthetics or medicines into the CSF. Medicines may
be injected to treat
leukemia and other types of cancer of the central
- Put a dye in the CSF that makes the spinal cord and
fluid clearer on X-ray pictures (myelogram).
This may be done to see whether a disc or a cancer is bulging into the spinal
In rare cases, a lumbar puncture may be used to lower the
pressure in the brain caused by too much CSF.
How To Prepare
Before you have a lumbar puncture, tell
your doctor if you:
- Are taking any medicines. If you take medicines
every day, ask your doctor whether you should take these medicines on the day
of the lumbar puncture.
- Are allergic to any medicines, such as
those used to numb the skin (anesthetics).
- Have had
bleeding problems or take blood-thinners, such as aspirin, warfarin
(Coumadin), or clopidogrel (Plavix).
- Are or might be pregnant.
- Take any herbal
remedies. Some of these remedies may thin the blood.
You will empty your bladder before the procedure.
You will be asked to sign a consent form that says you understand the risks of the test and agree to have it done.
your doctor about any concerns you have regarding the need for the procedure,
its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
How It Is Done
A lumbar puncture may be done in your
doctor's office, in an emergency room, or at your bedside in the hospital. It
may also be done in the radiology department if
fluoroscopy is used.