Lumbar Puncture

What is a lumbar puncture (also called spinal tap)?

A lumbar puncture, or spinal tap, is a procedure in which a fine needle is inserted into the spinal canal to obtain fluid surrounding the spinal cord (called the cerebrospinal fluid, or CSF).

This procedure may be performed to:

  • Look for infections, such as meningitis
  • Relieve pressure in the head, such as from intracranial hypertension or normal pressure hydrocephalus
  • Detect abnormalities of cells and proteins for various disorders, such as cancer, inflammatory diseases and multiple sclerosis

Testing spinal fluid may also help physicians diagnose disorders of the central nervous system that may involve the brain, spinal cord or other coverings.

Lumbar punctures are also used to administer antibiotics, cancer drugs or anesthetic agents into the spinal canal.

What happens during this procedure?

During the test, you will be asked to either lie down on your side with your knees drawn close to your chest and your neck flexed, or to remain in a seated position.

After cleaning the skin with antiseptic, sterile cloths (called drapes) will be placed around an area in your lower back. A local anesthetic (pain‐relieving medication) will be injected into that area. Once the area is numb, a needle is put into your lower back between the vertebrae to collect a sample of spinal fluid.

How long will the test take?

Although the actual procedure may take 10 minutes to a half‐hour, you should anticipate being at Cedars‐Sinai for up to two hours. You may experience a little discomfort in your lower back but it should subside quickly. Results can usually be determined within 48 hours.

For an appointment, a second opinion or more information, please call 1‐800‐CEDARS‐1 (1‐800‐233‐ 2771) or e‐mail us at