Robert Wood Johnson University Hospital
 

Lumbar Puncture (LP)

Lumbar Puncture (LP)

(Spinal Tap, Spinal Puncture, CSF Collection)

Procedure overview

What is a lumbar puncture?

A lumbar puncture (LP), also known as a spinal tap, is a diagnostic and/or therapeutic procedure performed by a doctor. The procedure is performed by inserting a hollow needle into the subarachnoid space in the lumbar area (lower back) of the spinal column. The subarachnoid space is the canal in the spinal column that carries cerebrospinal fluid (CSF) between the brain and the spinal cord.

CSF is a clear fluid that bathes the brain and spinal cord while protecting it, like a cushion, from exterior injury. The fluid is produced and reabsorbed in the brain on a continuous basis. CSF is composed of cells, water, proteins, sugars, and other vital substances that are essential to maintain equilibrium in the nervous system.

An illustration of the anatomy of the spine
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Other related procedures that may be used to diagnose problems with the spine or brain include myelography (myelogram), computed tomography (CT scan), or magnetic resonance imaging (MRI). Please see these procedures for additional information.

Anatomy of the spine

The spinal column is made up of 33 vertebrae that are separated by spongy disks and classified into distinct areas:

The spinal cord, a major part of the central nervous system, is located in the vertebral canal and reaches from the base of the skull to the upper part of the lower back. The bones of the spine and a sac containing cerebrospinal fluid surround it. The spinal cord carries sense and movement signals to and from the brain and controls many reflexes.

Reasons for the procedure

A lumbar puncture may be performed for various reasons. The most common reason is to remove a small amount of CSF for examination and diagnosis of various disorders. CSF is tested for red and white blood cells, protein, glucose (sugar), clarity, color, and the presence of bacteria, viruses, or abnormal cells. Excess CSF may also be removed in patients who have an overproduction or decreased absorption of the fluid.

A lumbar puncture procedure may be helpful in diagnosing many diseases and disorders including, but not limited to, the following:

In addition, a lumbar puncture may be used to measure the pressure of the CSF, which flows freely between the spinal column and the brain. The doctor measures the pressure during a lumbar puncture using a special tube (called a manometer) that is attached to the lumbar puncture needle.

Finally, a lumbar puncture may be performed therapeutically to inject medications directly into the spinal cord. Some medications that may be given via lumbar puncture (intrathecally) include: spinal anesthetics before a surgical procedure, contrast dye for X-ray studies (for example, myelography), or chemotherapeutic agents to treat cancer.

There may be other reasons for your doctor to recommend a lumbar puncture.

Risks of the procedure

Because this procedure involves the spinal cord and brain, the following potential complications may occur:

There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.

Before the procedure

During the procedure

A lumbar puncture procedure may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your doctor's practices.

Generally, a lumbar puncture follows this process:

Illustration of lumbar puncture
Click Image to Enlarge
  1. You will be asked to remove any clothing, jewelry, or other objects that may interfere with the procedure.
  2. You will be given a gown to wear.
  3. You will be reminded to empty your bladder prior to the start of the procedure.
  4. During the lumbar puncture you may lie on the examination table on your side with your chin tucked to your chest and knees tucked to your abdomen. Alternatively, you may sit on the edge of an examination table with your arms draped over a table positioned in front of you. In either position the back is arched, which helps to widen the intervertebral spaces.
  5. A lumbar puncture is a sterile procedure. Therefore, your back will be cleansed with an antiseptic solution and draped with sterile towels. The doctor will wear sterile gloves during the procedure.
  6. The doctor will anesthetize the skin by injecting a local anesthetic that numbs the site. This injection may sting for a few seconds, but makes the lumbar puncture less painful.
  7. The hollow needle will be inserted through the numbed skin and into the subarachnoid space where the CSF is located. You will feel some pressure while the needle is inserted. You must remain absolutely still during the insertion of the needle.
  8. The CSF will begin to drip out of the needle and a small amount, about one tablespoon, will be collected into test tubes.
  9. If the doctor needs to inject medication into the spinal canal, it will be given through the same needle after the CSF is collected.
  10. When the procedure is completed, the needle will be removed and an adhesive bandage will be placed over the injection site. The test tubes will be taken to the laboratory for analysis.
  11. You should notify the doctor if you feel any numbness, tingling, headache, or lightheadedness during the procedure.

You may experience discomfort during a lumbar puncture. The doctor will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain.

After the procedure

You usually will be asked to lie flat for about one hour after the lumbar puncture is completed. This helps reduce the incidence of a headache. You will be allowed to roll from side to side as long as your head is not elevated. If you need to urinate, you may be asked to urinate in a bedpan or urinal during the time that you are required to stay flat.

You will be asked to drink additional fluids to rehydrate after the procedure. This replaces the CSF that was withdrawn during the spinal tap and reduces the chance of developing a headache.

When you have completed the recovery period, you may be taken to your hospital room (if the procedure was performed elsewhere in the hospital) or discharged to your home. If you go home, usually your doctor will advise you to only engage in very light activity the rest of the day.

Once you are at home, notify your doctor of any abnormalities, such as numbness and tingling of the legs, drainage of blood or pain at the injection site, inability to urinate, or headaches. If the headaches persist for more than a few hours after the procedure, or when you change positions, you should contact your doctor.

You may be instructed to limit your activity for 24 hours following the procedure. Generally, if no complications occur, you may return to your normal diet and activities.

Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.

Online resources

The content provided here is for informational purposes only, and was not designed to diagnose or treat a health problem or disease, or replace the professional medical advice you receive from your doctor. Please consult your health care provider with any questions or concerns you may have regarding your condition.

This page contains links to other websites with information about this procedure and related health conditions. We hope you find these sites helpful, but please remember we do not control or endorse the information presented on these websites, nor do these sites endorse the information contained here.

American Academy of Neurological and Orthopaedic Surgeons

American Academy of Orthopaedic Surgeons

National Cancer Institute (NCI)

National Institute of Neurological Disorders and Stroke

National Institutes of Health (NIH)

National Library of Medicine

 

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