What is a lumbar puncture?

A lumbar puncture, also called a spinal tap, is a procedure in which the fluid surrounding the spinal cord (called the cerebrospinal fluid or CSF) is withdrawn through a needle and examined in a laboratory.

This procedure may be performed to:

  • measure the pressure around the brain and spinal cord
  • relieve pressure in the head and spinal canal
  • give spinal anesthesia
  • inject dye for an x-ray diagnostic test
  • inject medications

There are seven cervical vertebrae in the neck, 12 thoracic vertebrae in the torso and five lumbar vertebrae in the lower back. The needle used in a lumbar puncture is usually inserted between the lumbar vertebrae.

The cerebrospinal fluid (CSF) circulates in the subarachnoid space of the spinal canal. The CSF has many vital functions, including protecting the brain and spinal cord from injury. The CSF contains glucose (sugar), proteins, and other substances that are also found in the blood. Testing the CSF can help in the diagnosis of disorders of the central nervous system that may involve the brain, spinal cord, or their coverings (meninges).

Who performs the test?

The lumbar puncture procedure is performed by a physician trained in the use of X-ray equipment, called fluoroscopic equipment, which allows the doctor to view the needle as it is placed into the subarachnoid space.

Notify your physician

Before you have the procedure, inform your physician of any medications you are currently taking, including non-prescription drugs. Also tell your physician if you are allergic to any medications.

NOTE: Do not discontinue any medication without consulting with your primary care physician and/or the physician requesting this study.

If you have any of the following conditions, please notify your physician:

Before the test

A blood test or other laboratory tests may be ordered by your doctor prior to the test. Please follow these guidelines before the test:


The Department of Radiology recommends the medication restrictions listed below (after you check with your prescribing physician):

  • If you take Plavix, stop taking it 5 days before the procedure.
  • If you take Coumadin, stop taking it 5 days before the procedure.
  • If you are on Lovenox injections, do not take your morning dose the day of your procedure.
  • DO take your other medications as determined by your physician, especially any medications for high blood pressure.
  • We may make exceptions to these recommendations based upon your specific circumstances.
  • If you have questions or concerns regarding these restrictions, please call 216.445.6818.

Ask your doctor for specific guidelines regarding alcohol use before the test. Generally, you should not consume any alcohol for at least 24 hours before the test.

If you have diabetes:

  • Take your usual dose of insulin and eat a light breakfast before 8:00 a.m.
  • When you arrive for your test, please be sure to remind the physician that you have diabetes.
  • Insulin pumps will usually be removed if x-ray is considered or if defibrillation is a possibility.

Eating and drinking

There are no special diet restrictions associated with this procedure, unless otherwise instructed.

On the day of your test:

  • Please make arrangements for transportation, as you should not drive immediately after the test.
  • Please do not bring valuables such as jewelry or credit cards.
  • If you are unable to make your scheduled arrival time, please notify the schedulers at 216.444.6381.

You will meet with the radiologist in the Department of Radiology, DeskQb-1. In addition to providing verbal consent, you will discuss:

  • the steps of the procedure;
  • risks and benefits anticipated in your case, and;
  • any questions you may have about the procedure.

During the test:

  • The radiologist and technologist will be in the room with you.
  • Pre-medication, although rarely needed, may make you feel drowsy and relaxed.
  • You will wear a hospital gown during the examination.
  • You will either lie on your side with your knees bent, or on your stomach with a small pillow beneath your lower abdomen.
  • Your back will be cleaned with an antiseptic solution and sterile cloths (called drapes) will be placed around the area.
  • A local anesthetic (pain-relieving medication) will be injected into the area on your back. You may feel a slight burning sensation that lasts only seconds.
  • When the area is numb, a hollow needle is inserted in the lower back between two lumbar vertebrae. This sometimes causes pressure, but pain will be limited by the anesthetic.
  • The spinal canal is penetrated, and fluid is collected and/or medication is injected. The spinal cord is not touched by the needle during the test.
  • You may feel some discomfort or have a minor headache at the end of the procedure.
  • The needle is removed after the medication has been injected or fluid is removed. The area will be cleaned with an antiseptic solution and covered with a small bandage.
  • You will lie on your back for 30-60 minutes, depending on the nature of the procedure.
  • A blood sample may be taken from a vein in your arm and tested, along with the spinal fluid, in the laboratory.

After the test

You will be monitored in Radiology Recovery for 30-60 minutes. At that time, the Radiology nurse will discuss post-procedure instructions with you. You will be provided with a written form of these instructions. Please follow these instructions at home.

The results of your study will be discussed with your referring physician within 24 hours.

For the first 24 hours after the test:

  • Remain flat on your back as much as possible.
  • Drink at least 2 1/2 quarts of fluid.
  • Avoid heavy exercise or heavy lifting for 24 hours after the procedure.
  • Notify the Imaging Institute if you have any persistent drainage from the puncture site, or headache.

Please call the Division of Radiology if you have any questions:

216.445.6818, or 1.800.223.2273, extension 56818 (Monday-Friday, 7:30 AM to 4:00 PM)

After hours and on weekends:

For interventional radiology: call the interventional radiologist on call (1.800.223.2273, ask for pager 26446).


© Copyright 1995-2014 The Cleveland Clinic Foundation. All rights reserved.

This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 12/18/2014...9252