Lumbar puncture

Last updated: July 5, 2023

Summarytoggle arrow icon

Lumbar puncture (LP) is a diagnostic and/or therapeutic procedure in which a spinal needle is passed into the subarachnoid space and cerebrospinal fluid (CSF) is removed, CSF opening pressure is measured, and/or medications are injected. CSF analysis may aid in the diagnosis of meningitis, intracranial hemorrhage, multiple sclerosis, and meningeal carcinomatosis. Drainage of CSF is used in the treatment of idiopathic intracranial hypertension and normal pressure hydrocephalus. Untreated elevated intracranial pressure, bleeding disorders, and spinal abscesses are contraindications to lumbar puncture. CNS imaging and/or correction of coagulopathies should be considered prior to performing a lumbar puncture if the risk caused by procedural delay is acceptable. Post-lumbar puncture headache is a common complication, especially in young women, and is often accompanied by nausea and visual changes. The severity of post-lumbar puncture headache ranges from mild to incapacitating. Pharmacologic or interventional management may be necessary.

Indicationstoggle arrow icon

CSF testing for CNS diseases [1]

Urgent indications for lumbar puncture include suspected meningitis and SAH with negative CT scan.

CSF pressure measurement and/or drainage

Intrathecal administration of pharmaceuticals

Contraindicationstoggle arrow icon

Prior to LP, an effort should be made to identify potential contraindications and reduce patient risk. [1][2]

We list the most important contraindications. The selection is not exhaustive.

Technical backgroundtoggle arrow icon

Spinal needles [2]

  • Design
    • Atraumatic (e.g., Whitacre, Sprotte needles): lower rates of post-lumbar puncture headache, fewer traumatic taps
    • Cutting bevel (e.g., Quincke): fewer failed procedures, faster fluid collection
  • Size
    • Small (≥ 24 gauge): fewer complications, more procedure failures
    • Large (≤ 22 gauge): faster procedure time, faster fluid collection

A 20-gauge or 22-gauge atraumatic needle is recommended for most diagnostic lumbar punctures. [5][6]

Anatomical structures

Landmarks and positioningtoggle arrow icon


In adults, lumbar puncture is most commonly performed in the midline of the L3-L4 or L4-L5 interspace.

To keep the spinal cord alive, insert the needle between L3 and L5.


To accurately measure opening pressure, the patient must be in the lateral recumbent position. [1]

Equipment checklisttoggle arrow icon

Prepackaged kits usually contain most of the materials needed for lumbar puncture. Familiarize yourself with the kit used at your institution. [7]

Preparationtoggle arrow icon

Procedure/applicationtoggle arrow icon

Accessing the subarachnoid space [1]

  1. Infiltrate local anesthesia into the skin over the needle entry site with a 25-gauge needle.
  2. Infiltrate local anesthesia into the deep tissue along the needle tract with a 22-gauge needle.
  3. Place the spinal needle at the entry site and orient it towards the umbilicus.
  4. Advance the needle slowly until a loss of resistance is felt.
  5. Remove the stylet and look for CSF flow from the needle hub.
    • CSF flow: Proceed with pressure measurement and/or CSF collection.
    • No CSF flow: Replace the stylet and advance slowly until loss of resistance occurs again.

Obtaining opening CSF pressure

  1. Attach the manometer with a three-way stopcock to the needle hub.
  2. Turn the stopcock so the manometer opening is contiguous with the needle hub.
  3. Allow the manometer to fill until the level has equilibrated.

CSF collection [6]

  1. If a manometer is attached to the needle, turn the three-way stopcock to allow CSF to drain from the manometer.
  2. Fill pre-numbered sample tubes in sequential order.
    • A minimum of 1–2 mL is required in each tube. [3]
    • Use only passive flow: Do not aspirate CSF.
    • A total collection volume up to 30 mL is considered safe. [2]
  3. Reinsert the stylet, withdraw the needle from the patient, and apply a dressing to the puncture site.

Pitfalls and troubleshootingtoggle arrow icon

Unable to access subarachnoid space

  • Prevention
    • Position the patient with as much lumbar and hip flexion as possible. [9]
    • Use enough local anesthetic to minimize patient discomfort and movement.
    • Check for successful dural puncture with frequent stylet withdrawal. [10]
  • Management
    • Change needle trajectory. [1]
    • Reposition the patient if lumbar flexion is suboptimal.
    • Consider using a higher or lower interspace.
    • Consider using a long spinal needle. [11]
    • Consider radiology consult for lumbar puncture under fluoroscopy. [12]

Consult a more experienced provider if lumbar puncture is unsuccessful after four attempts. [2]

Postprocedure checklisttoggle arrow icon

  • CSF collection tubes labeled and transported to lab [6]
  • Procedure documented
  • Relevant CSF studies ordered

Interpretation/findingstoggle arrow icon

Cerebrospinal fluid analysis [13][14]

Opening pressures (see also elevated intracranial pressure and brain herniation)

Appearance Cell type (number/μL) Lactate Protein Glucose
  • ≤ 15 mm Hg
  • Colorless and transparent
  • 1.2–2.1 mmol/L
  • 15–45 mg/100 mL
  • 40–75 mg/100 mL (60% of serum levels)

Multiple sclerosis

  • Normal
  • Colorless and transparent
  • Normal
  • Normal to ↑
  • Normal

Guillain-Barré syndrome

  • Normal
  • Colorless and transparent
  • Normal
  • ↑↑
  • Normal

Subarachnoid hemorrhage, stroke

  • Normal or ↑ [15]
  • Bloody or xanthochromic (i.e., pink or yellow if hemorrhage > 6 h prior to sampling)
  • Normal
  • Normal

Brain tumors

  • Normal or ↑
  • Colorless and transparent
  • Normal

Pseudotumor cerebri (idiopathic intracranial hypertension)

  • ↑↑
  • Colorless and transparent
  • Acellular
  • Normal
  • Normal
  • Normal


  • ↑–↑↑
  • Colorless and transparent or cloudy
  • Variable
  • Normal or ↑
  • Normal or ↓

Disruption of the blood-brain barrier (i.e., infections, autoimmune diseases, CNS malignancies) or intrathecal production of IgG (i.e, multiple sclerosis, CNS infections such as Lyme disease) → increased immunoglobulins (oligoclonal bands) → increased CSF protein!

Complicationstoggle arrow icon

Post-lumbar puncture headache [1][2][17]


Post-lumbar puncture headache is caused by CSF leakage after intentional or accidental lumbar puncture.

Risk factors

  • Female sex
  • < 40 years of age
  • Low BMI [18]

Clinical features

  • Frontal or occipital headache
    • Typically worsens when patient is upright and improves when patient is supine
    • Presents up to 48 hours after the procedure
    • Generally lasts 1–2 days but may persist for months
  • Nausea, vomiting, dizziness, tinnitus, and visual disturbances
  • Symptoms may be mild to incapacitating.



  • Supportive care
  • Epidural blood patch
    • Indicated in severe refractory post-lumbar puncture headache
    • Technique: epidural injection of autologous blood at the site of lumbar puncture
    • Typically performed by an anesthesiologist or interventional radiologist


Use a small-gauge (e.g., ≥ 24 gauge), atraumatic needle for lumbar puncture.


Severe back pain and/or neurological deficits that begin after a lumbar puncture should raise concern for epidural hematoma.

We list the most important complications. The selection is not exhaustive.

Referencestoggle arrow icon

  1. Roberts JR. Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care. Elsevier ; 2018
  2. Engelborghs S, Niemantsverdriet E, Struyfs H, et al. Consensus guidelines for lumbar puncture in patients with neurological diseases. Alzheimers Dement (Amst). 2017; 8: p.111-126.doi: 10.1016/j.dadm.2017.04.007 . | Open in Read by QxMD
  3. Wright BLC, Lai JTF, Sinclair AJ. Cerebrospinal fluid and lumbar puncture: a practical review. J Neurol. 2012; 259 (8): p.1530-1545.doi: 10.1007/s00415-012-6413-x . | Open in Read by QxMD
  4. Horlocker TT, Vandermeuelen E, Kopp SL, Gogarten W, Leffert LR, Benzon HT. Regional Anesthesia in the Patient Receiving Antithrombotic or Thrombolytic Therapy. Reg Anesth Pain Med. 2018; 43 (3): p.263-309.doi: 10.1097/aap.0000000000000763 . | Open in Read by QxMD
  5. Reichman EF. Reichman's Emergency Medicine Procedures, 3rd Edition. McGraw Hill Professional ; 2018
  6. Gopal AK, Whitehouse JD, Simel DL, Corey GR. Cranial Computed Tomography Before Lumbar Puncture. Arch Intern Med. 1999; 159 (22): p.2681.doi: 10.1001/archinte.159.22.2681 . | Open in Read by QxMD
  7. Teunissen CE, Petzold A, Bennett JL, et al. A consensus protocol for the standardization of cerebrospinal fluid collection and biobanking. Neurology. 2009; 73 (22): p.1914-1922.doi: 10.1212/wnl.0b013e3181c47cc2 . | Open in Read by QxMD
  8. Seehusen DA, Reeves MM, Fomin DA. Cerebrospinal fluid analysis. Am Fam Physician. 2003; 68 (6): p.1103-1108.
  9. Deisenhammer F, Bartos A, Egg R, et al. Guidelines on routine cerebrospinal fluid analysis. Report from an EFNS task force. Eur J Neurol. 2006; 13 (9): p.913-922.doi: 10.1111/j.1468-1331.2006.01493.x . | Open in Read by QxMD
  10. Walls R, Hockberger R, Gausche-Hill M, Erickson TB, Wilcox SR. Rosen's Emergency Medicine 10th edition- Concepts and Clinical Practice E-Book. Elsevier Health Sciences ; 2022
  11. Choi PP, Shapera S. Drop metastases. CMAJ. 2006; 175 (5): p.475.doi: 10.1503/cmaj.060308 . | Open in Read by QxMD
  12. American Society of Anesthesiologists statement on post-dural puncture headache management. Updated: October 13, 2021. Accessed: March 6, 2023.
  13. Peralta F, Higgins N, Lange E, Wong CA, McCarthy RJ. The Relationship of Body Mass Index with the Incidence of Postdural Puncture Headache in Parturients. Anesth Analg. 2015; 121 (2): p.451-456.doi: 10.1213/ane.0000000000000802 . | Open in Read by QxMD
  14. Carson D, Serpell M. Choosing the best needle for diagnostic lumbar puncture. Neurology. 1996; 47 (1): p.33-37.doi: 10.1212/wnl.47.1.33 . | Open in Read by QxMD
  15. Fisher A, Lupu L, Gurevitz B, Brill S, Margolin E, Hertzanu Y. Hip flexion and lumbar puncture: a radiological study. Anaesthesia. 2001; 56 (3): p.262-266.doi: 10.1046/j.1365-2044.2001.01717-4.x . | Open in Read by QxMD
  16. Kathirgamanathan A, Hawkins N. Reliability of the ‘pop’ sign as an indicator of dural puncture during obstetric spinal anaesthesia: a prospective observational clinical study. Anaesthesia. 2007; 62 (8): p.802-805.doi: 10.1111/j.1365-2044.2007.05099.x . | Open in Read by QxMD
  17. Fati N, Fitiwi G, Aynalem A, Muche A. Depth of spinal needle insertion and its associated factors among patients who underwent surgery under spinal anesthesia. Transl Res Anat. 2021; 25: p.100143.doi: 10.1016/j.tria.2021.100143 . | Open in Read by QxMD
  18. Hudgins PA, Fountain AJ, Chapman PR, Shah LM. Difficult Lumbar Puncture: Pitfalls and Tips from the Trenches. AJNR Am J Neuroradiol. 2017; 38 (7): p.1276-1283.doi: 10.3174/ajnr.a5128 . | Open in Read by QxMD

Icon of a lock3 free articles remaining

You have 3 free member-only articles left this month. Sign up and get unlimited access.
 Evidence-based content, created and peer-reviewed by physicians. Read the disclaimer