MedicineNet.com
MedicineNet home Picture Slideshows Diseases and conditions Symptoms and signs Procedures and tests Medications Health and Living Health news and views MedTerms medical dictionary
Font Size
A
A
A


Lumbar Puncture (LP)

What is a lumbar puncture (LP)?

A lumbar puncture (an LP) is the insertion of a needle into the fluid within the spinal canal. It is termed a "lumbar puncture" because the needle goes into the lumbar portion (the "small") of the back.

Other names for a lumbar puncture (an LP) include spinal tap, spinal puncture, thecal puncture, and rachiocentesis.

Why is a lumbar puncture done?

An LP is most commonly peformed to diagnose a disease, namely to obtain a sample of the fluid in the spinal canal (the cerebrospinal fluid) for examination.

An LP can also be done to treat diseases. For example, as a way of administering antibiotics, cancer drugs, or anesthetic agents into the spinal canal. Spinal fluid is sometimes removed by LP for the purpose of decreasing spinal fluid pressure in patients with uncommon conditions (such as, for examples, normal-pressure hydrocephalus and benign intracranial hypertension).

How is the LP performed?

The patient is typically lying down sideways for the procedure. Less often, the procedure is performed while the patient is sitting up. LPs in infants are often done upright.

After local anesthesia is injected into the small of the back (the lumbar area), a needle is inserted in between the nearby bony building blocks (vertebrae) into the spinal canal. (The needle is usually placed between the 3rd and 4th lumbar vertebrae).

What is done next?

Spinal fluid pressure can then be measured and cerebrospinal fluid (CSF) removed for testing.

What is the cerebrospinal fluid (CSF)?

The CSF circulates around the brain and spinal cord (the central nervous system). This "water bath" acts as a support of buoyancy for the brain and spinal cord. The support of the CSF helps to protect the brain from injury.

The normal CSF contains various chemicals, such as protein and sugar (glucose), and few if any cells. The spinal fluid also has a normal pressure when first removed.



Next: What is normal CSF? »

Printer-Friendly Format  |  Email to a Friend


Suggested Reading by Our Doctors
MedicineNet Doctors
  • CT Scan (Computerized Axial Tomography) - CT Scan (Computerized Axial Tomography, CAT scan) is a procedure that assists in diagnosing tumors, fractures, bony structures, and infections in the organs and tissues of the body.
  • Multiple Sclerosis - Learn about the types of multiple sclerosis and symtpoms including muscle weakness and spasm, fatigue, memory loss, depression, memory loss, impaired judgement and more.
  • MRI (Magnetic Resonance Imaging Scan) - Medical information on magnetic resonance imaging (MRI) used in detecting structural abnormalities of the body. Learn uses, risks, and how to prepare for an MRI scan

Latest Medical News


Living Better

Find the secrets to longer life.




Symptoms & Signs A-Z List Pinpoint Your Symptoms - Start Now Symptoms & Signs A-Z List Symptoms & Signs by Female Body Region Symptoms & Signs by Male Body Region

Topics Related to Lumbar Puncture


Lumbar Puncture
RSS FeedSpecialty RSS       Add to My Yahoo! What is this?

Summer Headache Triggers Summer Headache Triggers
Does summer heat make your head feel like a pressure cooker? Get tips on how to cope with hot weather headaches.See more WebMD Videos »













Health categories:

Slideshows | Diseases & Conditions | Symptoms & Signs | Procedures & Tests | Medications | Health & Living | News & Views | Medical Dictionary

Popular health centers:

Allergies | Arthritis | Cancer | Diabetes | Digestion | Healthy Kids | Heart | Men's Health | Mental Health | Women's Health | More...

Publications:

ePublications (PDFs) | XML News via RSS | Audio Podcasts | Email Newsletters

MedicineNet.com:

About Us | Privacy Policy | Search Help | Site Map | WebMD® | Medscape® | eMedicine® | eMedicineHealth® | RxList®

This website is certified by Health On the Net Foundation. Click to verify. This site complies to the HONcode standard for trustworthy health information:
verify here.

©1996-2009 MedicineNet, Inc. All rights reserved. Notices and Legal Disclaimer.
MedicineNet does not provide medical advice, diagnosis or treatment. See additional information.