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  1. Diagnosis of meningitis, other infective or inflammatory disorders, subarachnoid hemorrhage, hepatic encephalopathy, meningeal malignancies, paraneoplastic disorders, or suspected intracranial pressure abnormalities.

  2. Assessment of therapeutic response in meningitis, infective or inflammatory disorders.

  3. Administration of intrathecal medications or radiologic contrast media.

  4. Rarely, to reduce cerebrospinal fluid (CSF) pressure.

  5. In specialized centers, assessment of biomarkers of certain degenerative diseases, especially Creutzfeldt-Jakob disease and Alzheimer disease, and of narcolepsy.


  1. Suspected intracranial mass lesion—Lumbar puncture can hasten incipient transtentorial herniation.

  2. Local infection over site of puncture. Use cervical or cisternal puncture instead.

  3. Coagulopathy—Correct clotting-factor deficiencies and thrombocytopenia (platelet count below 50,000/μL or rapidly falling) before lumbar puncture to reduce risk of hemorrhage.

  4. Suspected spinal cord mass lesion—In this case, remove only a small quantity of CSF to avoid creating a pressure differential above and below the block, which can increase spinal cord compression.


A. Personnel

With a cooperative patient, one person can perform lumbar puncture. An assistant may be helpful in patient positioning and sample handling especially if the patient is uncooperative or frightened.

B. Equipment and Supplies

The following are usually included in preassembled trays and must be sterile:

  1. Gloves

  2. Iodine-containing solution for sterilizing the skin

  3. Sponges

  4. Drapes

  5. Lidocaine (1%)

  6. Syringe (5 mL)

  7. Needles (22- and 25-gauge)

  8. Spinal needles (preferably 22-gauge) with stylets

  9. Three-way stopcock

  10. Manometer

  11. Collection tubes

  12. Adhesive bandage

C. Positioning

The lateral decubitus position is usually used (Figure 2-1) with the patient lying at the edge of the bed facing away from the clinician. Have the patient maximally flex the lumbar spine to open the intervertebral spaces with the spine parallel to the bed surface and hips and shoulders aligned in the vertical plane.

Figure 2-1.

Lateral decubitus position for lumbar puncture.

When a seated position is necessary, have the patient sit on the side of the bed, bent over a pillow on a bedside table, and reach over the bed from the opposite side to perform the procedure.

D. Site of Puncture

Most often, puncture is at the L3-L4 (level of posterior iliac crests) or L4-L5 vertebral interspace because the spinal cord (conus medullaris) terminates just above, approximately at L1-L2, in adults. Thus, with puncture below that level, there is no danger of puncturing the cord.


  1. For blood and CSF glucose level comparison, draw venous blood for glucose determination. Ideally, obtain simultaneous blood and CSF samples after the patient has fasted for at least 4 hours.

  2. Place necessary equipment and supplies in easy reach.

  3. Wear ...

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