lumbar puncture

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pertaining to the loins.
lumbar puncture introduction of a hollow needle into the subarachnoid space of the spinal canal, usually between the fourth and fifth lumbar vertebrae; see also cisternal puncture. Called also spinal puncture.

It may be done for diagnostic purposes to determine the pressure within the cerebrospinal cavities, to determine presence of an obstruction to flow of cerebrospinal fluid, to remove a specimen of cerebrospinal fluid for laboratory examination, or to inject air or other contrast medium into the spinal canal to take an x-ray of the cerebrospinal system.
Patient Care. Before the procedure is begun the patient is given a simple explanation of the nature and purpose of the test and is told that there is no danger of damage to the spinal cord during a lumbar puncture because the spinal cord does not extend below the second lumbar vertebra. For a cisternal puncture, the back of the neck may be shaved.

The patient is positioned so that the knees and head are flexed as much as possible and is assisted in maintaining this position during the entire procedure. A local anesthetic is injected subcutaneously to anesthetize the skin and underlying tissues. The patient should be warned not to move suddenly and told there may be a slight feeling of pressure when the puncture needle is inserted.

Strict adherence to the rules of aseptic technique is necessary to avoid the possibility of introducing microorganisms into the spinal canal. The attendant may be asked to assist in the Queckenstedt test during the lumbar puncture. This test involves compression of the veins of the neck, first on one side, then on the other and finally on both sides at once. The cerebrospinal fluid pressure is measured each time the veins are compressed. This test determines whether there is an obstruction in the spinal canal. Care must be taken that the trachea is not constricted while the neck veins are being compressed.

After the procedure the patient is observed for signs of pulse changes, respiratory difficulty, or cyanosis. These rarely occur, but headache is common and may be partially relieved by keeping the patient flat in bed for 8 hours after the procedure. An ice cap and aspirin may help alleviate the discomfort.
Technique of lumbar puncture. Needle is inserted between vertebrae and advanced through dura mater to the subarachnoid space. Cerebrospinal fluid is thus withdrawn from the spinal cavity.


1. the act of piercing or penetrating with a pointed object.
2. a wound so made.
cisternal puncture see cisternal puncture.
lumbar puncture (spinal puncture) see lumbar puncture.
sternal puncture see sternal puncture.
tracheoesophageal puncture surgical creation of a tracheoesophageal fistula to hold a one-way plastic valve to restore speech after Laryngectomy.

lum·bar punc·ture (LP),

a puncture into the subarachnoid space of the lumbar region to obtain spinal fluid for diagnostic or therapeutic purposes.

lumbar puncture

The insertion of a hollow needle beneath the arachnoid membrane of the spinal cord in the lumbar region to withdraw cerebrospinal fluid for diagnostic purposes or to administer a drug.

lumbar puncture (LP)

a diagnostic or therapeutic procedure in which a hollow needle and stylet are introduced into the subarachnoid space of the lumbar part of the spinal canal to obtain cerebrospinal fluid (CSF). Strict aseptic technique is used. Diagnostic indications include measuring of CSF pressure; obtaining CSF for laboratory analysis; and injecting oxygen or a radiopaque substance for radiographic visualization of the structures of the nervous system of the spinal canal and meninges and brain. Therapeutic indications for lumbar puncture include removing blood or pus from the subarachnoid space, injecting sera or drugs, withdrawing CSF to reduce intracranial pressure, introducing a local anesthetic to induce spinal anesthesia, and placing a small amount of the patient's blood in the subarachnoid space to form a clot to patch a hole in the dura to prevent leak of CSF into the epidural space.
method The skin over the interspace of the third and fourth lumbar vertebrae is cleansed. A fenestrated sterile drape is placed over the back, the window over the puncture site. The needle is inserted through the interspace to the subarachnoid space, and the stylet is withdrawn. If the needle is in the proper place, clear, straw-colored CSF will begin to drip out through the needle. Depending on the indication for the procedure, various techniques follow. The pressure of the CSF may be measured with a manometer attached to a catheter and stopcock, or fluid may be withdrawn, visually examined, and sent to the laboratory for chemical or bacteriological analysis.
interventions The nurse may be responsible for obtaining the patient's written permission for the physician to perform a lumbar puncture. If the patient is apprehensive, he or she may be given a sedative one-half hour before the procedure. The techniques to be used and the treatments to be given or the information to be obtained are explained. The patient is placed in a lateral recumbent position, the back as near the edge of the bed as possible. The legs are flexed on the thighs, the thighs are flexed on the abdomen, and the head and shoulders are bent down, curving the spine convexly to afford the greatest space between the vertebrae. If the patient is excessively hairy, a dry shave of the lumbar area is performed before draping the area. After the procedure, significant signs to be observed by the nurse include pain, change in mentation or alertness, leakage of CSF from the puncture site, fever, and urinary retention. The patient is usually kept flat in bed, often in a prone position, for 1 hour after the procedure.
outcome criteria Lumbar puncture is contraindicated if intracranial tumor is suspected and there is evidence of greatly increased intracranial pressure, if there are signs of infection at the site of puncture, or (to avoid a second puncture) if encephalography or myelography is planned in the near future. Infection, leakage of CSF, headache, nausea, vomiting, dysuria, or signs of meningeal irritation occur in approximately 25% of patients.
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Lumbar puncture

lumbar puncture

Spinal tap Neurology A diagnostic procedure in which a very long needle is inserted into the subarachnoid space between the 3rd and 4th lumbar vertebrae in order to obtain CSF; an LP is used to measure intracranial pressure, which may be ↑ 2º to hemorrhage, tumors, or edema, measure CSF chemistries–eg, glucose, proteins, diagnose inflammation of the CNS, especially infections–eg, meningitis, and stroke, spinal cord tumors and metastases to the CNS, or inject a dye into the spine before myelography Complications Uncommon; meningitis, bleeding into spinal canal; if intracranial pressure is ↑, removal of CSF from spinal canal may cause fatal herniation of cerebellar tonsils. See Cerebrospinal fluid.

lum·bar punc·ture

(lŭm'bahr pŭngk'shŭr)
Synonym(s): rachicentesis, rachiocentesis, spinal tap.
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lumbar puncture

Abbreviation: LP
Gaining entry into the subarachnoid space of the meningeal sac below the end of the spinal cord, usually at the level of the fourth intervertebral space with a hollow needle. This procedure is done to obtain cerebrospinal fluid (CSF) for analysis, as in the diagnosis of severe headache or in suspected central nervous system infection or bleeding; to administer drugs to the brain or spinal cord (such as anesthetics or chemotherapeutic agents); or to relieve the CSF of excess pressure or fluid, as in pseudotumor cerebri. Synonym: spinal puncture; Quincke puncture; spinal tap See: illustration; cisternal puncture; headache; Queckenstedt sign


Postprocedure headache occurs in about half of all patients who undergo lumbar puncture. Rarely reported complications of the procedure include cerebral herniation, epidural infection, epidural bleeding, paraparesis, and subdural bleeding.


Informed consent for the procedure is obtained except in dire emergencies when clinical judgment prevails. Appropriate equipment is gathered: sterile gloves and mask for the operator, skin antiseptic (povidine-iodine solution), local anesthetic (1% lidocaine), and a lumbar puncture tray containing sterile gauze sponges, fenestrated drape and towel, needles and syringe for anesthesia, spinal needles, 4 collection tubes, 3-way stopcock and manometer; and a small adhesive bandage.

The procedure and expected sensations are explained, and the patient is asked to remain still when positioned and to breathe normally. The patient is typically placed on his or her left side at the right edge of the bed or examining table with knees drawn up to the abdomen and chin down to the chest, or in a sitting position with legs over one side of the table and buttocks at the other, bending head and chest toward the knees. Either of these positions exposes the back to the operator and provides spinal flexion, allowing easy access to the lumbar subarachnoid space. The assisting nurse holds the patient appropriately to secure this position (one arm around the neck, the other around the knees, or holding both shoulders bent forward). Draping provides warmth and privacy. Next, the patient's skin is prepared with antiseptic solution, and a sterile fenestrated barrier is placed over the proposed puncture site. Local anesthetic is injected, and then the spinal needle, with its stylet in place, is slowly advanced between the vertebra into and through the dura and arachnoid membranes. The stylet that fills the needle is removed, and initial measurements are made of the opening intracranial pressure (ICP) with a manometer. When the procedure is performed for diagnosis, about 8 to 10 ml of fluid are collected and sent promptly to the clinical laboratory for analysis of cell count, glucose, protein levels, cultures stains, and special studies. The closing pressure should then be read, the needle removed, and a small impervious adhesive dressing applied, sometimes with collodion to prevent CSF leakage. See: illustration


Pain at the puncture site, infection, bleeding, neurological injury, death, and post–spinal tap headaches are all potential complications. Of these, postural headache, caused by chronic leakage from the puncture site, is the complication most often brought to the attention of health care professionals. It may be treated with the injection of a small amount of the patient's own blood epidurally, to form a blood patch. See: cerebrospinal fluid

Patient care

The nurse assists the operator throughout the procedure by numbering and capping specimen tubes for laboratory examination and by applying jugular vein pressure as directed. Reassurance and direction are provided to the patient throughout the procedure, and the patient is assessed for adverse reactions (elevated pulse rate, pain radiating into the limbs, pallor, clammy skin, or respiratory distress).

After the procedure, the nurse assesses vital signs and neurological status, particularly observing for signs of paralysis, weakness, or loss of sensation in the lower extremities. If CSF pressure is elevated, the patient’s neurological status should be assessed every 15 min for 4 hr, if normal, every hour for 2 hr, then every 4 hr or as ordered. The puncture site should be checked hourly for 4 hr, then every 4 hr for 24 hr, assessing for redness, swelling, and drainage. To decrease the chance of headache, oral intake (for spinal fluid replacement and equalization of pressures) is encouraged, and the patient should remain in bed in a supine position or with the head elevated no more than 30° for 4 to 24 hr (per operator or institutional protocol). The patient should not lift his or her head but can move it (and himself or herself) from side to side. Noninvasive pain relief measures and prescribed analgesia are provided if headache occurs.

See also: puncture

lumbar puncture

Passage of a needle between two vertebrae of the spine, from behind, into the fluid-filled space lying below the termination of the spinal cord. Lumbar puncture is usually done to obtain a sample of cerebrospinal fluid for laboratory examination in the investigation of disorders of the nervous system. It also allows antibiotic drugs, anaesthetic agents and radio-opaque substances to be injected.

Lumbar puncture

A procedure in which the doctor inserts a small needle into the spinal cavity in the lower back to withdraw some spinal fluid for testing. Also known as a "spinal tap."


Heinrich Irenaeus, German physician, 1842-1922.
Quincke capillary pulsation - Synonym(s): Quincke pulse
Quincke disease - Synonym(s): Quincke edema
Quincke edema - recurrent, large, circumscribed areas of subcutaneous edema of sudden onset, usually disappearing within 24 hours. Synonym(s): angioedema; Milton disease; Milton urticaria; Quincke disease; Quincke I syndrome
Quincke meningitis - intracranial hypertension of unknown origin.
Quincke needle
Quincke pulse - capillary pulsation, a sign of arteriolar dilation and especially well seen in severe aortic insufficiency. Synonym(s): Quincke capillary pulsation; Quincke sign
Quincke puncture - a puncture into the subarachnoid space of the lumbar region to obtain spinal fluid for diagnostic or therapeutic purposes. Synonym(s): lumbar puncture
Quincke sign - Synonym(s): Quincke pulse
Quincke spinal needle
Quincke I syndrome - Synonym(s): Quincke edema


pertaining to the loins.

lumbar epidural analgesia
see epidural anesthesia.
lumbar paralysis
paraplegia generally and specifically that due to cerebrospinal nematodiasis.
lumbar plexus
one formed by the ventral branches of the last four or five lumbar nerves in the psoas major muscle.
lumbar puncture
insertion of a needle and stylet into the subarachnoid space between the seventh lumbar vertebra and sacrum in most species except the dog, where the space between the sixth and seventh lumbar vertebrae is usually used; called also spinal puncture. A lumbar puncture may be done to measure the pressure of cerebrospinal fluid and obtain a specimen for examination, and to inject a contrast medium for special radiographic examinations such as myelography. As a therapeutic measure it is sometimes done to relieve intracranial pressure or to remove blood or pus from the subarachnoid space. A lumbar puncture also is necessary for injection of a spinal anesthetic.
lumbar spinal stenosis
see lumbosacral stenosis.
lumbar tap
see lumbar puncture (above).
lumbar vertebrae
the vertebrae between the thoracic vertebrae and the sacrum, numbering seven in dogs and cats, six in horses and cattle, and six or seven in sheep and pigs.