Epilepsy: Lumbar Puncture (Spinal Tap)

http://www.webmd.com/epilepsy/lumbar-puncture-spinal-tap

WebMD Medical Reference in Collaboration with The Cleveland Clinic

What Is a Lumbar Puncture?

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tap, which is a procedure in which the fluid surrounding the spinal cord (called the cerebrospinal fluid or CSF) is withdrawn through a needle and examined in a laboratory.

Why Is the Lumbar Puncture Procedure Performed?

This procedure may be performed to:

• Measure the pressure around the brain and spinal cord.
• Relieve pressure in the head.
• Give spinal anesthesia.
• Inject dye for an X-ray diagnostic test.
• Inject medications (such as haclofen).

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). The CSF contains glucose (sugar), proteins and other substances found in the blood. When the CSF is examined in the laboratory, the following are evaluated:

• The number and types of white blood cells.
• The level of glucose.
• The types and levels of proteins.
• The presence of bacteria, fungi or abnormal cells.

NOTE: Testing of the CSF may not be necessary if the spinal tap procedure is done to inject a medication (such as haclofen).

What to Expect

Preparation for the procedure

• Maintain your regular eating schedule. There are no dietary or fluid restrictions before the test.
• Ask your doctor for specific guidelines about discontinuing alcohol use, aspirin products and anticoagulant medications before the procedure.
• Tell your doctor if you are allergic to latex or any medications.
• Please make arrangements for transportation, as you should not drive immediately after the test.

Description of the procedure

You will either lie on your side with your knees drawn as close to your chest as possible and your chin toward your chest or sit with your arms and head resting on a table. After cleaning your back with an antiseptic, 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. When the area is numb, a hollow needle is inserted in the lower back between two lumbar vertebrae. This sometimes causes pressure. The spinal canal is penetrated and fluid is collected 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. The needle is removed after the medication has been injected or fluid is removed. The area will be covered with a small bandage. A blood sample will be taken from a vein in your arm and tested, along with the spinal fluid, in the laboratory. NOTE: if the procedure was done to inject medication, a blood sample may not be taken.

Side effects and risks of the procedure

• Approximately 10% to 20% of people develop a spinal headache (one that worsens when sitting or standing).
• The risk of infection is extremely low.
• Occasionally, a small blood vessel is pierced, causing bloody discharge. No treatment is needed.
• The procedure is usually not painful, but momentary twinges of pain may be felt if the needle brushes against nerve tissue.

Care after the procedure

• Once a spinal tap is completed, you will be instructed to lie flat. The time spent flat after the tap will vary depending on why you received the procedure.
• Avoid strenuous or vigorous exercise for a day or so following the lumbar puncture.
• If you have a headache, lay down as much as possible and drink plenty of fluids. Contact your health care provider if the headache persists.
• Drink 2 1/2 quarts of liquid the day of the lumbar puncture and the day after (regardless of headache).

When to Contact the Doctor

Call your local doctor immediately if:

• You notice any unusual drainage, including bloody discharge, at the puncture site.
• You develop a fever.
• Your headache persists.
• Your pain symptoms worsen.

After the Test:

You will be monitored for a few hours. At that time, the nurse will discuss post-procedure instructions with you. You will be provided with a written form of these instructions to follow 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:

1. Remain flat on your back as much as possible.
2. Drink at least 2 1/2 quarts of fluid.
3. Notify your doctor if you experience any drainage from the puncture site, or develop a headache.

Lumbar Puncture (LP)

http://www.cooperhealth.org/content/greystone_21917.htm




(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 physician. 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.

Click Image to Enlarge

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 cervical area consists of seven vertebrae in the neck.
• The thoracic area consists of 12 vertebrae in the chest area.
• The lumbar area consists of five vertebrae in the lower back area.
• The sacrum has five, small fused vertebrae.
• The four coccygeal vertebrae fuse to form one bone, called the coccyx or tailbone.

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:

• meningitis - an inflammation of the membrane covering the brain and spinal cord. The inflammation is usually the result of a viral, bacterial, or fungal infection, or the result of exposure to toxins or abnormal cells.
• encephalitis - an inflammation of the brain that is usually caused by a virus.
• certain cancers involving the brain and spinal cord
• bleeding in the subarachnoid space
• Reye syndrome - a potentially fatal disease that causes severe problems with the brain and other organs. Although the exact cause of the disease is not known, there has been an association between giving aspirin to children and the development of Reye syndrome. It is now advised not to give aspirin to children during illnesses, unless prescribed by your child's physician.
• myelitis - an inflammation of the spinal cord or bone marrow.
• neurosyphilis - a stage of syphilis during which the bacteria invades the central nervous system.
• Guillain-Barré syndrome - a disorder in which the body's immune system attacks part of the nervous system.
• demyelinating diseases - diseases that attack the protective coating that surrounds certain nerve fibers (e.g., multiple sclerosis or acute demyelination polyneuropathy).

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 physician 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 (e.g., myelography), or chemotherapeutic agents to treat cancer.

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

Risks of the Procedure

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

• A small amount of CSF can leak from the needle insertion site. This can cause headaches after the procedure.
• There is a slight risk of infection because the needle breaks the skin’s surface, providing a possible portal of entry for bacteria.
• A temporary numbness to the legs or lower back pain may be experienced.
• There is a risk of bleeding in the spinal canal.
• Should there be increased pressure or swelling in the brain before the procedure, a lumbar puncture can cause fluctuations in the CSF fluid levels, resulting in brain herniation. Herniation is a dangerous event in which the brain stem or top of the spinal column is compressed by swelling of the brain.

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

Before the Procedure

• Your physician will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.
• You will be asked to sign a consent form that gives your permission to do the procedure. Read the form carefully and ask questions if something is not clear.
• Generally, fasting is not required prior to a lumbar puncture unless a sedative is prescribed. Your physician will instruct you prior to the procedure of any necessary fasting requirements.
• Notify your physician if you are pregnant or suspect you may be pregnant.
• Notify your physician of all medications (prescribed and over-the-counter) and herbal supplements that you are taking.
• Notify your physician if you have a history of seizures or if you are taking any prescribed medications for seizures.
• Notify your physician if you have a history of bleeding disorders or if you are taking any anticoagulant (blood-thinning) medications, aspirin, or other medications that affect blood clotting. It may be necessary for you to stop these medications prior to the procedure.
• If the procedure is performed on an outpatient basis, you may be asked to remain in the hospital for several hours following the procedure. You should plan to have another person drive you home.
• Based upon your medical condition, your physician may request other specific preparation.

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 physician's practices.

Generally, a lumbar puncture follows this process:

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 physician will wear sterile gloves during the procedure.
6. The physician 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 physician 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 physician if you feel any numbness, tingling, headache, or lightheadedness during the procedure.

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

After the Procedure

You will be asked to lie flat for up to eight hours 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. You may be asked to urinate in a bedpan 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.

Once you are at home, notify your physician 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 physician.

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 physician 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 physician. Please consult your physician with any questions or concerns you may have regarding your condition.

This page contains links to other Web sites 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 Web sites, nor do these sites endorse the information contained here.

American Academy of Neurological and Orthopaedic Surgeons

American Academy of Orthopedic Surgeons

National Cancer Institute

National Institute for Neurological Disorders and Stroke

National Institutes of Health (NIH)

National Library of Medicine

Spinal Tap

http://www.emedicinehealth.com/spinal_tap/article_em.htm



Spinal Tap Introduction

• A spinal tap is a procedure performed when a doctor needs to look at the cerebrospinal fluid (also known as spinal fluid). Spinal tap is also referred to as a lumbar puncture, or LP.
  
  
• Some of the reasons your doctor may want to do a spinal tap include the following:
  
  
  • To look for infection
    
    
  • To check to see if there is bleeding around the brain (subarachnoid hemorrhage)
    
    
  • To look for causes of unexplained seizures
    
    
  • To look for causes of headaches
  
  
• Cerebrospinal fluid is a liquid that bathes the brain and spinal cord. An adult has about 140 mL (just under 5 oz) of spinal fluid. Typically, an adult makes 30-100 mL of spinal fluid daily.
  
  
• A spinal tap can be performed in any person and at any age from newborn to age 100 years and older.

Risks

Although infrequent, several complications can occur as a result of a spinal tap.

• Headache
  
  
  • About 5-30% of people who have a spinal tap get what is commonly referred to as post –lumbar puncture headache.
    
    
  • Your headache may start up to 48 hours after the procedure and usually lasts for 2 days or less.
    
    
  • The headache typically worsens when you are in an upright position and lessens when you lie flat.
    
    
  • The cause of the headache is leakage of the spinal fluid from around the puncture site.
    
    
  • Younger people and males have an increased risk of headaches after lumbar puncture compared with older people and females.
    
    
  • You reduce your chance of getting one of these headaches by drinking plenty of fluids, especially caffeine products such as tea, coffee, and cola.
    
    
  • Occasionally, a blood patch is needed. An anesthesiologist or pain management specialist injects a small amount of your own blood at the site where the spinal tap was performed. You usually experience relief within 30 minutes after this procedure.
  
  
• Herniation
  
  
  • A herniation can occur if an abscess (pocket of infection) or increased intracranial pressure (ICP) is present during your spinal tap.
    
    
  • If the pressure in your brain is elevated when the spinal tap is performed, the flow of fluid from the brain down the cord may cause the brain to get squeezed down into the direction of the spinal cord. This is extremely rare and occurs only with elevated intracranial pressure.
    
    
  • If a person has signs and symptoms consistent with meningitis (fever, headache, and stiff neck), then the spinal tap may be performed immediately. In some people, a CT scan of the brain is performed first, however, to rule out the possibility of bleeding or other causes that may increase the pressure within the skull or around the brain.
    
    
  • If increased intracranial pressure is suspected, great caution is taken and your condition is carefully discussed before a spinal tap is performed, if it is performed at all.
  
  
• Bleeding
  
  
  • Injury to the blood vessels that surround the covering of the spinal canal may occur when the needle is being inserted. Frequently referred to as a traumatic tap, this may cause a small amount of localized bleeding.
    
    
  • Sometimes this can affect the results of the procedure, which would mean that the doctor would have to re-insert the needle into another area of the back, frequently an inch or so away from the first site. Proper numbing medicine, if needed, is injected to decrease any pain.
    
    
  • The spinal cord ends at the level of the first or second lumbar vertebrae, and the needle is usually inserted at a level between the third and fourth or the fourth and fifth lumbar vertebrae, keeping the spinal cord completely out of danger.
  
  
• Epidermoid cyst
  
  
  • Rarely, certain tissues (epidermoid) are accidentally implanted into the spinal canal when the spinal tap is performed.
    
    
  • The likelihood of an epidermoid cyst is much greater when a needle without a stylet is used, and this almost never occurs today. All spinal tap kits used today have needles with stylets.

Spinal Tap Preparation

• No special preparation is needed on your part before a spinal tap.

• Always ask your doctor to fully explain the process to you as she or he is doing it. This talking through helps to lessen any anxiety that you may experience.

During the Procedure

Most spinal taps can be completed within 5-10 minutes.

• You are asked to lie on your side with your legs and hips bent (flexed) up toward your chest and your neck slightly bent forward. This position is often called the fetal position. (Some doctors place you in a seated position, where you lean forward and rest your arms on a tray or back of a chair. This is an acceptable alternative position.)

• The doctor always wears sterile gloves and occasionally also wears a mask and gown.

• The spinal tap is performed using sterile technique, meaning that everything used is sterilized to minimize any risk of infection.

• The doctor next identifies landmarks on your body. Frequently, the doctor does this by feeling the top of the pelvis bone (on your side). This area corresponds with the fourth and fifth lumbar space where the needle is inserted.

• A numbing medication (lidocaine) is injected first into your skin and then into the deeper tissues of your lower back to numb the area completely. This injection causes some minor discomfort, which is usually brief and has been described as a burning sensation.

• You should inform the doctor at any time if you feel pain when the procedure is being performed.

• The needle is then inserted in your lower back, usually at the third and fourth lumbar or fourth and fifth lumbar level. The needle passes between the 2 vertebrae to enter the space where the fluid is contained. Placing you in the fetal position allows the vertebral spaces to open more widely to make needle passage easier.

• Occasionally, the doctor may measure the pressure within the fluid containing area. This does not change the procedure nor does it affect the results.

• The fluid is then allowed to collect into a series of 3 or 4 vials that are then sent to the lab for evaluation.

• The fluid collects passively, meaning it is allowed to drip out into each vial at its own pace. This step can take several minutes for a full specimen collection.
  
  
• After the fluid is collected, the needle is removed and a bandage or small dressing is placed over the area.

After the Procedure

• You may be asked to lie flat on your back for a time after the spinal tap. This is to reduce the possibility of headaches. Drinking fluids, especially caffeine products such as tea, coffee, and cola can also help to reduce headaches.

• Your puncture site may be sore for 1-2 days.

• As with any procedure where the skin is punctured, the area should be monitored for signs of infection. Redness, swelling, pus from the area, or tenderness to touch should prompt immediate attention from a doctor.

Next Steps

• Depending on the reason for the spinal tap, follow-up care may or may not be necessary.

• If the tap is performed in the emergency department, then you are frequently instructed to follow up in 24-48 hours, either with your doctor or in the emergency department.

• If the spinal tap is performed in a doctor’s office, then a follow-up telephone call may be suggested, or a follow-up appointment may be scheduled to discuss the results of the tests, especially if specialized testing is ordered.

When to Seek Medical Care

You should contact your doctor if any of the following occur:

• Infection

• Rarely, infection at the site where the needle was inserted may occur.
  
  
• Signs and symptoms include redness, swelling, tenderness, or pus from the site.

• Headache

• Headaches can occur after a spinal tap and occasionally may be severe.
  
  
• If this occurs, you should contact your doctor.

Any signs or symptoms of infection or severe headache should prompt immediate attention from your doctor. If you are unable to reach your doctor, then you should seek immediate attention from your local emergency department.

Multimedia

Media file 1: The lower portion of the back, or lumbar region. The doctor is pointing to the area where the needle will be inserted between the third and fourth vertebrae. Notice the other hand on the top of the pelvis bone serving to help locate this area. (For orientation purposes, the patient is on the right side with the head off to the right side of the screen.)

Media type: Photo

Media file 2: An example of the sterile technique used. A drape is placed around the area (the blue sheet), and then the needle is put in place. (The glass tube going up from the needle is the device used to measure the pressure of the fluid itself.)


Media type: Photo

Media file 3: The fluid is allowed to collect into each of the vials so that it can be sent to the lab for analysis.


Media type: Photo

Synonyms and Keywords

spinal tap, lumbar puncture, spinal puncture, cerebrospinal fluid analysis, LP

References

1. Cooper JR. Routine use of CT prior to lumbar puncture. Br J Radiol. Mar 1999;72(855):319. [Medline].

2. Gonzalez DP. Lumbar puncture headache exacerbated by recumbent position. Mil Med. Sep 2000;165(9):vi, 690. [Medline].

3. Greenhall R. Lumbar puncture. Br Med J. Mar 15 1980;280(6216):796. [Medline].

4. Kooiker JC, Roberts JR, Hedges JR. Spinal puncture and cerebrospinal fluid examination. In: Clinical Procedures in Emergency Medicine. 2^nd ed. 1991:969-84.

5. Linden CH, James WA, Hartigan CF. Cranial computed tomography before lumbar puncture. Arch Intern Med. Oct 9 2000;160(18):2868-70. [Medline].

6. Schull M, Tintinalli JE. Headache and facial pain. In: Emergency Medicine: A Comprehensive Study Guide. 5^th ed. 2000:1429.

7. Tattevin P, Bruneel F, Régnier B. Cranial CT before lumbar puncture in suspected meningitis. N Engl J Med. Apr 18 2002;346(16):1248-51; author reply 1248-51. [Medline].

8. Thomas SR, Jamieson DR, Muir KW. Randomised controlled trial of atraumatic versus standard needles for diagnostic lumbar puncture. BMJ. Oct 21 2000;321(7267):986-90. [Medline].

9. Vallejo MC, Mandell GL, Sabo DP, Ramanathan S. Postdural puncture headache: a randomized comparison of five spinal needles in obstetric patients. Anesth Analg. Oct 2000;91(4):916-20. [Medline].

Authors and Editors

Author: Scott D Fell, DO, FAAEM, Medical Director, Emergency Care Center, Bon Secours Venice Hospital.

Coauthor(s): Christina L Kukula, DO, Consulting Staff, Walk-in-Care Center, Bon Secours Venice Hospital.

Editors: Scott H Plantz, MD, FAAEM, Research Director, Assistant Professor, Department of Emergency Medicine, Mount Sinai School of Medicine; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Thomas Rebbecchi, MD, FAAEM, Program Director, Assistant Professor, Department of Emergency Medicine, University of Medicine and Dentistry of New Jersey.

Last Editorial Review: 10/20/2005

Lumbar Puncture (or Spinal Tap)

http://www.health.harvard.edu/diagnostic-tests/lumbar-puncture.htm

What is the test?

A lumbar puncture, also known as a spinal tap, uses a needle to remove a sample of fluid from the space surrounding the spinal cord. This fluid is known as cerebrospinal fluid (CSF). The test is used to diagnose meningitis infections and some neurological conditions.

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How do I prepare for the test?

You will need to sign a consent form, which is generally required when the procedure is done outside of an emergency situation. Tell your doctor ahead of time if you have ever had an allergic reaction to lidocaine or the numbing medicine used at the dentist's office.

Doctors routinely do a physical examination and in some cases order a brain scan before recommending a lumbar puncture, to make sure you do not have a medical condition that could put you at risk for movement of the brain during the procedure, a very rare but serious complication.

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What happens when the test is performed?

Most patients wear a hospital gown. Typically, you lie on your side with your knees curled up against your chest. In some cases, the doctor asks you to sit on the bed or a table instead, leaning forward against some pillows.

The doctor feels your back to locate your lower vertebrae and feels the bones in the back of your pelvis. An area on your lower back is cleaned with soap. Medicine is injected through a small needle to numb the skin and the tissue underneath the skin in the area from which the sample is to be removed. This causes some very brief stinging.

A different needle is then placed in the same area and moved forward until fluid can be obtained through it from the spinal canal. Because the needle must be placed through a small opening between two bones, the doctor must sometimes move the needle in and out several times to locate the opening. Because of the numbing medicine used in this area, most patients experience only a sense of pressure from this movement. Occasionally some patients do get a sharp feeling in the back or (rarely) in the leg. Let your doctor know if you feel any pain.

Sometimes the doctor measures the pressure of the fluid before taking a sample. The pressure is measured with a tube that looks like a large thermometer held against the needle. The fluid sample collected is usually less than three tablespoons. You will not feel any discomfort when it is removed. After this, the needle is taken out. Usually a Band-Aid is the only dressing necessary.

The whole lumbar puncture, including set-up time, takes 30–45 minutes. The needle is in place for close to one minute.

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What risks are there from the test?

The most common risk of a lumbar puncture is that it can cause a temporary headache. Lying down for a few hours after the test can make a headache less likely to occur. Other problems are rare and include infection or bleeding. Because the volume of fluid is small, a lumbar puncture almost never causes movement of the brain or spinal cord, a serious complication.

---

Must I do anything special after the test is over?

You may be told to lie flat for a while after the test, sometimes for a few hours.

---

How long is it before the result of the test is known?

Depending on the tests being done on the fluid sample, results take anywhere from a few hours to a few days.

Cerebral spinal fluid (CSF) collection

http://www.nlm.nih.gov/medlineplus/ency/article/003428.htm

Illustrations

CSF chemistry

Lumbar vertebrae

Alternative Names

Spinal tap; Ventricular puncture; Lumbar puncture; Cisternal puncture; Cerebral spinal fluid culture

Definition

Cerebral spinal fluid (CSF) collection is a test to look at the fluid that surrounds the brain and spinal cord. Cerebral spinal fluid acts like a cushion, protecting the brain and spine from injury. The fluid is normally clear. The test is also used to measure pressure in the spinal fluid.

See also: CSF culture

How the Test is Performed

There are different ways to get a sample of spinal fluid. Lumbar puncture, commonly called a spinal tap, is the most common method. The test is usually performed in the following manner:

• The patient must lay on his or her side, with the knees pulled up toward the chest, and the chin tucked downward. Sometimes the test is done with the person sitting up, but bent over.
• After the back is cleaned, the health care provider will inject a local numbing medicine (anesthetic) into the lower spine.
• A spinal needle is inserted, usually into the lower back area.
• Once the needle is properly positioned, spinal fluid pressure is measured, and fluid is collected.
• The needle is removed, the area is cleaned, and a bandage is placed over the needle site. The patient is often asked to lie down for a short time after the test.

Occasionally, special x-rays are used to help guide the needle into the proper position. This is called fluoroscopy.

Lumbar puncture with fluid collection may also be part of other procedures, particularly a myelogram (x-ray or CT scan after dye has been inserted into the CSF).

Alternative methods of CSF collection are rarely used, but may be necessary in the event of a back deformity or infection.

Cisternal puncture uses a needle placed below the occipital bone (back of the skull). It can be dangerous because it is so close to the brain stem.

Ventricular puncture is even more rare, but may be recommended in persons with possible brain herniation. This test is usually done in the operating room. A hole is drilled in the skull, and a needle is inserted directly into one of brain's ventricles.

How to Prepare for the Test

The patient (or guardian) must give the health care team permission to do the test.

How the Test Will Feel

The position may be uncomfortable, but it is extremely important that the patient stays in the bended position to avoid moving the needle and possibly injuring the spinal cord.

The anesthetic will sting or burn when first injected. There will be a hard pressure sensation when the needle is inserted, and there is usually some brief pain when the needle goes through the tissue surrounding the spinal cord. This pain should stop in a few seconds.

Overall, discomfort is minimal to moderate. The entire procedure usually takes about 30 minutes, but it may take longer. The actual pressure measurements and fluid collection only take a few minutes.

Why the Test is Performed

This test is done to measure pressures within the cerebrospinal fluid and to collect a sample of the fluid for further testing. CSF can be used to diagnose certain neurologic disorders, particularly infections (such as meningitis) and brain or spinal cord damage.

See also:

• CSF coccidioides complement fixation
• CSF oligoclonal banding
• CSF smear
• CSF VDRL test

Normal Results

Normal values vary from lab to lab but typically range as follows:

• Pressure: 50 - 180 mm H20
• Appearance: clear, colorless
• CSF total protein: 15 - 45 mg/100 mL
• Gamma globulin: 3 - 12% of the total protein
• CSF glucose: 50 - 80 mg/100 mL (or approximately 2/3 of blood sugar level)
• CSF cell count: 0 - 5 white blood cells, no red blood cells
• Chloride: 110 - 125 mEq per liter

Note: mg/mL = milligrams per milliliter; mEq/L = milliequivalent per liter

What Abnormal Results Mean

If the CSF looks cloudy, it could mean there is an infection or a build up of white blood cells or protein.

If the CSF looks bloody or red, it may be a sign of bleeding or spinal cord obstruction. If it is brown, orange, or yellow, it may be a sign of increased CSF protein or previous bleeding (more than 3 days ago).

Increased CSF pressure may be due to increased intracranial pressure (pressure within the skull). Decreased CSF pressure may be due to spinal cord tumor, shock, fainting, or diabetic coma.

Increased protein may be due to blood in the CSF, diabetes, polyneuritis, tumor, injury, or any inflammatory or infectious condition. Decreased protein is a sign of rapid CSF production.

Increased CSF gamma globulin levels may be due to diseases such as multiple sclerosis, neurosyphilis, or Guillain-Barre syndrome.

Increased CSF glucose is a sign of high blood sugar. Decreased CSF glucose may be due to hypoglycemia (low blood sugar), bacterial or fungal infection (such as meningitis), tuberculosis, or certain types of meningitis.

Increased white blood cells in the CSF may be a sign of meningitis, acute infection, beginning of a chronic illness, tumor, abscess,stroke, or demyelinating disease (such as multiple sclerosis).

Red blood cells in the CSF sample may be a sign of bleeding into the spinal fluid or the result of a traumatic lumbar puncture.

Additional conditions under which the test may be performed:

• Chronic inflammatory polyneuropathy
• Dementia due to metabolic causes
• Encephalitis
• Epilepsy
• Febrile seizure (children)
• Generalized tonic-clonic seizure
• Hydrocephalus
• Inhalation anthrax
• Normal pressure hydrocephalus (NPH)
• Pituitary tumor
• Reye syndrome

Risks

Risks of lumbar puncture include:

• Hypersensitivity (allergic) reaction to the anesthetic
• Discomfort during the test
• Headache after the test
• Bleeding into the spinal canal

There is an increased risk of bleeding in persons who take blood thinners.

Brain herniation may occur if this test is done on a person with a mass in the brain (such as a tumor or abscess). This can result in brain damage or death. This test is not done if an exam or test reveals signs of a brain mass.

Damage to the nerves in the spinal cord may occur, particularly if the person moves during the test.

Cisternal puncture or ventricular puncture carry additional risks of brain damage and bleeding within the brain.

Considerations

This test should not be performed on people who may have increased intracranial pressure.

References

Nathan, BR. Cerebrospinal Fluid and Intracranial Pressure. In: Goetz, CG, ed. Textbook of Clinical Neurology, 2nd ed. Philadelphia, Pa:WB Saunders Company; 2003:511-524.

Update Date: 4/30/2007 Updated by: Joseph V. Campellone, M.D., Division of Neurology, Cooper University Hospital, Camden, NJ. Review provided by VeriMed Healthcare Network.

Lumbar Puncture and Stroke

What is lumbar puncture?

This is a procedure to help doctors diagnose neurological conditions. (Neurological conditions are those that affect the nervous system.) Lumbar puncture has been an important diagnostic tool since it was introduced in 1891, but it’s now done only rarely in patients with stroke symptoms. It's also called spinal puncture or spinal tap.

The process involves taking samples of the cerebrospinal fluid (or CSF) from around the spinal cord. The tests are done on the fluid samples. This helps doctors gain important information:

• The presence of blood or blood products in the CSF suggests bleeding. Hemorrhagic strokes occur when an artery ruptures and bleeds into or onto the brain.
• CSF analysis can also indicate changes due to tumor, infection and inflammation. Infection and inflammation may lead to symptoms that mimic a stroke.
• Spinal puncture allows the doctor to quantify pressure within the central nervous system.

What other tests can be used to diagnose stroke?

Imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) can be done during acute stroke. In most cases they permit effective, safe diagnosis of ischemic stroke (caused by blood clots) and of bleeding into the brain. These tests largely eliminate the need for lumbar puncture in stroke. These imaging systems also help identify tumors and other conditions that mimic stroke. New monitoring devices can measure CSF pressure and detect changes in intracranial pressure. Pressure-induced shifts in regions of the brain can be imaged by CT and MRI.

Lumbar Puncture (LP)

http://www.medicinenet.com/lumbar_puncture/article.htm

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.

What is normal CSF?

Normal values for spinal fluid examination are as follows:

• Protein (15-45 mg/dl)
• Glucose (50-75 mg/dl)
• Cell count (0-5 mononuclear cells)
• Initial pressure (70-180 mm)

These normal values can be altered by injury or disease of the brain, spinal cord or adjacent tissues. The values are routinely evaluated during examination of the spinal fluid obtained from the lumbar puncture. Additionally, spinal fluid is tested for infection in the microbiology laboratory.

What diseases are diagnosed by examination of the CSF?

Spinal fluid obtained from the lumbar puncture can be used to diagnose many important diseases such as bleeding around the brain; increased pressure from hydrocephalus; inflammation of the brain, spinal cord, or adjacent tissues (encephalitis, meningitis); tumors of brain or spinal cord, etc. Sometimes spinal fluid can indicate diseases of the immune system, such as multiple sclerosis.

What are the risks of an LP?

When spinal fluid is removed during an LP, the risks include headache, brain herniation, bleeding, and infection. Each of these complications are uncommon with the exception of headache, whiSave as Draftch can appear from hours to up to a day after LP. Headaches occur less frequently when the patient remains lying flat 1-3 hours after the procedure.

What are the benefits of an LP?

The benefits of the LP depend upon the exact situation for which it is performed, but an LP can provide lifesaving information.

Reference:
Harrison's Principles of Internal Medicine, McGraw-Hill, edited by Eugene Braunwald, et. al., 2001.

Spinal puncture

http://www.bartleby.com/65/sp/spinalpu.html

The Columbia Encyclopedia, Sixth Edition. 2001-05.

Surgical penetration of the spinal canal by a hollow needle introduced between two of the lumbar vertebrae. The arrangement permits injection of antibiotics or anesthetics (see anesthesia) as well as dyes to facilitate X-ray studies. It also allows withdrawal of cerebrospinal fluid (CSF), the plasmalike liquid cushioning the brain and spinal cord, in which case the procedure is known as a spinal tap. Examination of the CSF is useful in diagnosing disease of the central nervous system. The fluid is first tested for pressure; a high reading may signal inflammation or tumor. If pressure is normal, a small sample can be taken. It is then analyzed for antibodies, white blood cells, cellular debris, bacteria, and other organisms. Unusual concentrations may indicate disorders such as spinal meningitis, polio, or cancer. The concentrations of protein, sugar, and other chemical components are also determined. Excessive protein may be a sign of spinal tuberculosis.

Lumbar puncture (spinal tap)

http://www.mayoclinic.com/health/lumbar-puncture/HQ01414

What does a spinal tap tell my doctor?

Mayo Clinic neurologist Jerry Swanson, M.D., and colleagues answer select questions from readers.

Answer

CLICK TO ENLARGE

Lumbar puncture (spinal tap)

A lumbar puncture, also called a spinal tap, removes a small amount of cerebrospinal fluid (CSF) — the fluid that protects your brain and spinal cord from injury — for laboratory analysis. The test also measures the pressure in CSF fluid. Results of a lumbar puncture can help diagnose:

• Serious infections, such as meningitis, polio and encephalitis
• Bleeding around the brain (subarachnoid hemorrhage)
• Certain cancers involving the brain and spinal cord
• Certain inflammatory conditions of the nervous system, such as multiple sclerosis and Guillain-Barre syndrome

During a lumbar puncture procedure, you typically lie on your side with your knees drawn up to your chest. A local anesthetic is injected in an area over your lower spine to reduce discomfort from the procedure. Then your doctor inserts a needle into your spinal canal, measures the pressure and collects fluid for analysis. The entire procedure usually takes about 45 minutes. Once the procedure is complete, you'll need to lie flat for 20 minutes to one hour.

Lab technicians check for a number of things when examining spinal fluid, including:

• General appearance. Spinal fluid is normally clear and colorless. If it is cloudy, it may indicate infection.
• Protein — total protein and the presence of certain proteins. Elevated levels of protein may indicate infection or other condition.
• White blood cells. Increased numbers of white cells in spinal fluid may indicate infection.
• Sugar (glucose). A low glucose level in spinal fluid may indicate infection or other condition.
• Bacteria and fungi.
• Polymerase chain reaction — which helps identify certain viruses such as meningitis.

Lumbar Puncture

http://www.webmd.com/brain/lumbar-puncture

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.

During a 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

A 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 subarachnoid hemorrhage).
• Diagnose certain diseases of the brain and spinal cord, such as multiple sclerosis or Guillain-Barré syndrome.
• 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:

• Put anesthetics or medicines into the CSF. Medicines may be injected to treat leukemia and other types of cancer of the central nervous system.
• 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 canal.

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 or warfarin (Coumadin).
• 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.

For a lumbar puncture, you will be asked to sign a consent form. Talk to 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. This procedure is often done in an emergency situation. If you are scheduled to have this procedure, you can understand the importance of it by filling 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.

You will lie on a bed on your side with your knees drawn up toward your chest. Or you may sit on the edge of a chair or bed and lean forward over a table with your head and chest bent toward your knees. These positions help widen the spaces between the bones of the lower spine so that the needle can be inserted more easily. If fluoroscopy is used, you will lie on your stomach so the fluoroscopy machine can take pictures of your spine during the procedure. See an illustration of a lumbar puncture.

Your doctor marks your lower back (lumbar area) with a pen where the puncture will occur. The area is cleaned with a special soap and draped with sterile towels. A numbing medicine (local anesthetic) is put in the skin.

Then a long, thin needle is put in the spinal canal. When the needle is in place, the solid central core of the needle (stylet) is removed. If the needle is in the right spot in the spinal canal, a small amount of cerebrospinal fluid (CSF) will drip from the end of the needle. If not, the stylet will be put back in and the needle will be moved in a little farther or at a different angle to get to the fluid. Your doctor may need to move to another area of your spine if it is hard to get to the spinal fluid.

When the needle is in the spinal canal, a device called a manometer is hooked to the needle to measure the pressure of the CSF. You may be asked to straighten your legs while you are lying down. Your doctor takes the pressure reading, called the opening pressure, and checks whether the fluid is clear, cloudy, or bloody. Several small samples of fluid are collected and sent to the lab for study.

A final pressure reading, called the closing pressure, may be taken after the fluid samples are done. The needle is taken out and the puncture site is cleaned and bandaged.

The entire procedure takes about 30 minutes.

To lower your chance of getting a headache following a lumbar puncture, you may be told to lie flat in bed or with your head slightly raised for 1 to 4 hours. Since your brain makes new CSF all the time and replaces it 2 to 3 times a day, the small amount of fluid that is removed will be quickly replaced. You may be told to drink extra fluids after the procedure to help prevent or to reduce the severity of a headache.

How It Feels

Some people find it uncomfortable to lie curled up on their side. The soap may feel cold on your back. You will probably feel a brief pinch or sting when the numbing medicine is given. You may feel a brief pain when the spinal needle is inserted or repositioned.

During the procedure, the needle may touch one of your spinal nerves and cause a tingling feeling, like a light electrical shock, running down one of your legs. The needle will not touch or damage the spinal cord.

Some people (10% to 25%) develop a headache after having a lumbar puncture. Of those who do get headaches, only about half report that they are severe. These headaches last 24 to 48 hours and go away on their own. Pain medicine does not help control the headache, but lying flat in bed for several hours after the procedure may help the headache.

You may feel tired and have a mild backache the day after the procedure. Some people have trouble sleeping for 1 to 2 days.

Risks

A lumbar puncture is generally a safe procedure. In some cases, a leak of cerebrospinal fluid (CSF) may develop after a lumbar puncture. Symptoms of this problem are a headache that does not go away after 1 to 2 days. A CSF leak can be treated with a blood "patch," in which the person's own blood is injected into the area where the leak is occurring in order to seal the leak.

About 1 in 1,000 people who have a lumbar puncture have a minor nerve injury. This heals on its own with time. There is also a small chance of infection of the CSF (meningitis), bleeding inside the spinal canal, or damage to the cartilage between the vertebrae. Your doctor will talk with you about these risks.

People who have bleeding problems and those who are taking blood-thinning medicine (such as warfarin or heparin) have a higher chance of bleeding after the procedure. A lumbar puncture may not be done unless it is needed for a life-threatening illness.

A lumbar puncture may cause serious problems for people who have high pressure in the brain caused by a tumor, a pocket of infection in the brain (abscess), or major bleeding inside the brain. Your doctor will check your nervous system, spinal cord and brain before doing a lumbar puncture. In some cases, a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan may be done before the lumbar puncture to know that it is safe to do the puncture.

After the procedure

Call your doctor immediately if you have:

• Chills or a fever.
• A stiff neck. This may be a sign of a developing infection.
• Any drainage or bleeding from the puncture site.
• A severe headache.
• Any numbness or loss of strength below the puncture site

Results

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. Many different tests can be done on the CSF. Some results will be ready right away, some will take a few hours after the procedure, and others will take several weeks.

Normal results

Appearance:	CSF is normally clear and colorless.
Pressure:	Normal CSF pressure in the lower back for an adult ranges from 80 to 200 millimeters (mm) water. For children, the normal opening pressure range is 30 to 60 mm water.
Protein:	The normal protein content of CSF in an adult's lower back (lumbar) region is 55 milligrams per deciliter (mg/dL) or less. Older adults and children may have higher values (up to 70 mg/dL) that are still in the normal range.
Glucose:	The normal range for glucose content in the CSF is at least 60% to 70% of the blood glucose level. The levels may be slightly increased if the person has just eaten.
Cell counts:	Normal CSF contains no red blood cells (RBCs). The white blood cell (WBC) count for adults is 0 to 5 WBCs per cubic millimeter (mm3). Children may normally have a higher WBC count. No neutrophils are present. Lymphocytes or monocytes are 0 to 4 per mm3.
Other results:	No infectious organisms (such as bacteria, fungi, or a virus) are found in the CSF sample. No tumor cells are present.

Abnormal results

Appearance:	Blood in the CSF can result from bleeding (hemorrhage) in or around the spinal cord or brain, but it may also be caused by tiny blood vessel poked during the spinal tap. If a brain hemorrhage has occurred, the Colour of the CSF may change from red to yellow to brown over several days. Bleeding caused by the lumbar puncture itself will show more red blood cells in the first sample collected than in later samples. Cloudy CSF may mean an infection (such as meningitis or a brain abscess) is present.
Pressure:	High CSF pressure may occur as a result of swelling (edema) or bleeding (hemorrhage) in the brain, infection (such as meningitis), stroke, or other circulatory problems. Below-normal pressure may mean a blocked spinal canal.
Protein:	A high level of protein may be caused by bleeding in the CSF, a tumour or spread of a cancer from another area of the body, diabetes, infection, injury, Guillain-Barré syndrome, severe hypothyroidism, or other nerve diseases. An increase in antibodies (immunoglobulins) may be caused by inflammation in people who have multiple sclerosis, immune system disorders, or other bacterial and viral diseases.
Glucose:	Low glucose levels in the CSF are abnormal and may be caused by bacterial meningitis. Viral meningitis does not often cause low glucose levels in the CSF. Brain hemorrhage may also cause low glucose levels several days after bleeding begins. Higher-than-normal glucose levels are often caused by diabetes.
Cell counts:	Red blood cells (RBCs) in the CSF means bleeding. High levels of white blood cells (WBCs) mean meningitis. Tumour cells and abnormal levels of white blood cells mean cancer.
Other results:	Antibodies, bacteria, or other organisms in the CSF means that an infection (such as syphilis) or disease is present. Bacterial markers (bacterial antigens) that show up mean meningitis. Cultures or stains of the CSF may also help show the cause of meningitis or encephalitis.

Your doctor may order other special tests on the CSF fluid depending on your symptoms and medical history.

What Affects the Test

Reasons you may not be able to have the biopsy or why the results may not be helpful include:

• Not being able to lie still during the procedure.
• Having conditions such as obesity, dehydration, spinal disease, severe arthritis, or recent spinal surgery. These conditions may make it hard to do a lumbar puncture with the person lying down. The procedure may need to be done with the person sitting up and bent forward. In some cases, the procedure may need to be done with a special X-ray method called fluoroscopy. This is used to guide the placement of the spinal needle.
• Bleeding into the cerebrospinal fluid (CSF). The needle puncture can cause bleeding into the CSF. Several samples of the fluid can show the difference between bleeding from the puncture and bleeding caused by a brain hemorrhage.
• Not being able to collect a sample of the fluid. This is called a "dry tap."

What To Think About

• A lumbar puncture is not done if the person has:
  • A suspected tumor, swelling, or increased pressure in the brain. A computed tomography (CT) scan or magnetic resonance imaging (MRI) scan may be done first to see if it is safe to do the lumbar puncture.
  • A skin infection on the lower back. Doing a lumbar puncture in this case may allow the infection to spread into the spinal canal.
  • Bleeding disorders, which may increase the chance of bleeding during the procedure.
• Other tests that may be done include:
  • A cisternal or ventricular puncture. Cerebrospinal fluid (CSF) can be collected from the upper spinal canal at the base of the skull (cisternal puncture) or from within the skull (ventricular puncture) when it is not possible to get CSF from the lumbar area. These procedures are done by a trained radiologist or neurosurgeon. Special X-ray methods are used to guide the placement of the needle.
  • Bacterial marker studies. In cases of suspected bacterial meningitis, bacterial marker (bacterial antigen) studies can quickly find the common types of bacteria that cause meningitis. Antibiotic treatment for that bacteria can be started immediately.

Other Works Consulted

• Fischbach FT, Dunning MB III, eds. (2004). Manual of Laboratory and Diagnostic Tests, 7th ed. Philadelphia: Lippincott Williams and Wilkins.

• Pagana KD, Pagana TJ (2006). Mosby’s Manual of Diagnostic and Laboratory Tests, 3rd ed. St. Louis: Mosby.

Author	Jan Nissl, RN, BS
Editor	Susan Van Houten, RN, BSN, MBA
Associate Editor	Tracy Landauer
Primary Medical Reviewer	Patrice Burgess, MD - Family Medicine
Specialist Medical Reviewer	Joseph O'Donnell, MD - Hematology
Last Updated	December 4, 2006