Lumbar Puncture Part 1: The Basics

a monthly blog series on procedures

Hunting & Gathering

Find a Workstation on Wheels (WOW) with a functioning Topaz to obtain informed consent.

Place Epic orders for CSF. Print the stickers and sign each with your initials.

Locate an LP tray,  its contents, sterile gloves, eye protection, facemask.

Gather these optional supplies:

  • Extra spinal needles:
    • 20 gauge, 3.5 in Quincke = cutting needle (1 included in tray).
    • 22 gauge, 3.5 in Whitacre = atraumatic needle.
    • 20 gauge, 6 in “Harpoon” = longer needle.
  • Extra 1% Lidocaine (5ml in tray).
  • Extra Povidone-Iodine.
  • Non-sterile marking pen.

Optional: Tech or RN for positioning assistance during procedure.


Perform the LP (see below).

Collect CSF in 4 tubes and send to lab.

Choosing the right needle

The Whitacre needle (aka a type of pencil point needle, or “atraumatic” needle) contains side ports, and theoretically causes less damage to tissue fibers upon entry. They are more difficult to use for skin entry. However, studies have shown that atraumatic needles decrease the incidence of post-LP headache (1 and 2). As an aside, there is no evidence that lying supine for any fixed period time is helpful in the prevention of post-LP headache(3).

Key indications for doing an LP in the ER

Suspicion of…

  • CNS infection
  • SAH

Other diagnoses to consider…

  • Guillain-Barré syndrome
  • Idiopathic intracranial hypertension

When NOT to perform the LP

  • Absolute contraindication: needle entry through infected skin or soft tissue
  • Relative contraindicationscoagulopathy (INR > 1.4) or severe thrombocytopenia (< 40)…theoretical risk of spinal epidural hematoma.
  • Other contraindication: Space-occupying lesion in the brain.
    • Although patients with mass lesions have undergone LPs without complication, the risk of brain herniation does exist (4)
    • Current literature suggests to obtain CT brain to rule out mass lesion if:
      • Age > 60 years
      • Immunocompromised
      • AMS or focal neuro deficits
      • Signs of elevated ICP
      • History of CNS lesion
      • Recent seizure


Roberts and Hedges LP

From Roberts & Hedges’ Clinical Procedures in Emergency Medicine, 6th ed, 2013

Useful additional resources:

NEJM Video LP Video (from Peter Kas)

Not covered here in detail, but check out these links on pediatric LP (Thanks, Dr. Merritt!):  

Infant LP Video (from Larry Mellick)

dontforgetthebubbles vodcast on LP (from Sobolewski and Jennings)

POISE Infant LP Video (from IPSS)

How to position your patient

Default patient position: Lateral recumbent with spine parallel to bed.


From proceduresconsult: lateral recumbent position.

Alternative patient position: Upright sitting with hips flexed with feet on a stool.


From proceduresconsult: sitting position.

How to position your needle

With your dominant hand, hold the hub of the needle, and with your non-dominant hand, place your thumb/index finger on the shaft of the needle for balance.

Keep the needle parallel to the bed, bevel up, aim toward umbilicus, midline.

lp holding needle

From proceduresconsult: needle entry. 

Where to insert the needle

The spinal cord usually terminates at L1 (and sometimes at L2) in adults. You can safely insert your needle in the following 4 interspaces: L2-L3, L3-L4, L4-L5, and L5-S1.

L3-L4 and L4-L5 are preferred (closer to the area of greatest flexion). The body of L4 is approximately at the level of the iliac crests (see picture below).

*NOTE: In children younger than 12 years, the spinal cord can extend to L3. 


From Roberts & Hedges’ Clinical Procedures in Emergency Medicine, 6th ed, 2013

How much CSF do you need?

Approximately 1 ml in tubes 1-3, and 3-4 ml in tube 4. The 4th tube is actually stored in the lab for any extra studies ordered down the line.



Textbook References

Euerle, B. Spinal Puncture and Cerebrospinal Fluid Examination. Chapter 60, 1218-1242.e3. In: Roberts J, et al. Roberts & Hedges’ Clinical Procedures in Emergency Medicine. 6th Saunders; 2013.

Article References

  1. Lavi R, Yarnitsky D, Rowe JM, Weissman A, Segal D, et al. Standard vs atraumatic Whitacre needle for diagnostic lumbar puncture: a randomized trial. Neurology. 2006 Oct 24;67(8):1492-4. PubMed PMID: 17060584
  2. Strupp M, Schueler O, Straube A, Von Stuckrad-Barre S, Brandt T. “Atraumatic” Sprotte needle reduces the incidence of post-lumbar puncture headaches. Neurology. 2001 Dec 26;57(12):2310-2. PubMed PMID: 11756618
  3. Thoennissen J, Herkner H, Lang W, Domanovits H, Laggner AN, et al. Does bed rest after cervical or lumbar puncture prevent headache? A systematic review and meta-analysis. CMAJ. 2001 Nov 13;165(10):1311-6. PubMed PMID: 11760976; PubMed Central PMCID: PMC81623
  4. Hasbun R, Abrahams J, Jekel J, Quagliarello VJ. Computed tomography of the head before lumbar puncture in adults with suspected meningitis. N Engl J Med. 2001 Dec 13;345(24):1727-33. PubMed PMID: 11742046.

Jonathan Ameli, MD

9 thoughts on “Lumbar Puncture Part 1: The Basics

  1. Fantastic!! Love the click through images (order sets, needles, etc)–this would be perfect for Just-in-Time teaching for newbies in the ED prior to procedure, or for them to study at home with the linked videos and references. Looking forward to part 2!

  2. Agreed with Megan and Gita, terrific post and should definitely be required reading for med students, EMPEDS and interns. Love the RIH specifics! Was thinking about this yesterday when I watched the link Gita posted for Scott Weingart’s ED thoracotomy tray, and how I’d love to see a RIH specific version.

  3. Good stuff. Sometimes I find that the wimpy vial of lidocaine in the tray isn’t enough, so after the timeout you can use “regular” lidocaine to really numb them up. The harpoon needle is so scary.

  4. Pingback: Lumbar Puncture Part 2: Pearls, Pitfalls, and Troubleshooting | Brown Emergency Medicine

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