EM · Procedural & diagnostic ED skills
Lumbar puncture in the emergency department
Also known as Lumbar puncture · LP · Spinal tap · Cerebrospinal fluid sampling · CSF analysis
Lumbar puncture in the ED — the indications (suspected meningitis or encephalitis, subarachnoid haemorrhage after a negative CT, demyelinating disease — multiple sclerosis, CIDP, Guillain-Barre, and the therapeutic uses — idiopathic intracranial hypertension, cryptococcal meningitis, intrathecal drug delivery), the safety screen (fast-track imaging where indicated but antibiotics inside the hour), the atraumatic needle in all patients, ultrasound-assisted localisation, careful CSF interpretation by cause/age/immunity, spectrophotometry for both pigments after a negative CT, and caffeine for established PDPHls, low glucose; viral — lymphocytes, normal glucose; TB — very low glucose, very high protein; SAH — xanthochromia and uniform red cells), and the post-dural puncture headache (atraumatic needle halves it; caffeine and the epidural blood patch treat it). ACEM-primary, globally tagged.
Checked against its sources on 13 Oct 2026
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Target exams
Red flags
- Blood cultures, lumbar puncture and antibiotics inside the first hour — rapid treatment reduces mortality and sequelae, so never let imaging delay therapy
- Use the atraumatic pencil-point needle in all patients, adults and children — traumatic needles carry risk ratio 2.14 for headache
- Spectrophotometry for both oxyhaemoglobin and bilirubin after a negative or equivocal CT — because CT can miss SAH
- PDPH is postural (worse within 15 minutes upright, better within 15 minutes flat) with a broad differential — caffeine treats at one to two hours
- Correct traumatic blood at 1 white cell per 1000 red cells — and distrust the correction above 100,000 red cells
Meet the patient
A 34-year-old man arrives with 24 hours of fever, severe headache, photophobia and neck stiffness. His GCS is 14, there is no focal deficit and no papilloedema. The Ottawa SAH rule is not met. You decide to perform a lumbar puncture.[2]
The two questions an examiner will press are the two that run this station: when do you image before the puncture? (the CT-first criteria) and how do you read the four tubes once they are drawn? (the cell count, glucose, protein, and the tube 1 to tube 4 red-cell comparison). Hold those two questions and the whole topic slots into place.[1]
References17ShowHide
- [1]Brouwer MC, Tunkel AR, van de Beek D. Epidemiology, diagnosis, and antimicrobial treatment of acute bacterial meningitis Clin Microbiol Rev, 2010.PMID 20610819
- [2]Brouwer MC, Tunkel AR, van de Beek D. Dilemmas in the diagnosis of acute community-acquired bacterial meningitis Lancet, 2012.PMID 23141617
- [3]Perry JJ, Sivilotti MLA, Émond M, et al. Validation of the Ottawa Subarachnoid Hemorrhage Rule in patients with acute headache CMAJ, 2017.PMID 29133539
- [4]Perry JJ, Wells JS, Sivilotti MLA, et al. Prospective Implementation of the Ottawa Subarachnoid Hemorrhage Rule and 6-Hour Computed Tomography Rule Stroke, 2020.PMID 31805846
- [5]Bezov D, Lipton RB, Ashina S, Ashina M. Post-dural puncture headache: part I diagnosis, epidemiology, etiology, and pathophysiology Headache, 2010.PMID 20533959
- [6]Bezov D, Ashina S, Lipton R, Ashina M. Post-dural puncture headache: Part II--prevention, management, and prognosis Headache, 2010.PMID 20807248
- [7]Arevalo-Rodriguez I, Muñoz L, Godoy-Casasbuenas N, et al. Needle gauge and tip designs for preventing post-dural puncture headache (PDPH) Cochrane Database Syst Rev, 2017.PMID 28388808
- [8]Rochwerg B, Almenawer SA, Siemieniuk RAC, et al. Atraumatic (pencil-point) versus conventional needles for lumbar puncture: a clinical practice guideline BMJ, 2018.PMID 29789372
- [9]Gottlieb M, Holladay D, Peksa GD. Ultrasound-assisted Lumbar Punctures: A Systematic Review and Meta-Analysis Acad Emerg Med, 2019.PMID 30129102
- [10]April MD, Long B, Koyfman A Emergency Medicine Myths: Computed Tomography of the Head Prior to Lumbar Puncture in Adults with Suspected Bacterial Meningitis - Due Diligence or Antiquated Practice? The Journal of emergency medicine, 2017.PMID 28666562
- [11]Chaudhuri A, Martinez-Martin P, Kennedy PG, et al. EFNS guideline on the management of community-acquired bacterial meningitis: report of an EFNS Task Force on acute bacterial meningitis in older children and adults. European journal of neurology, 2008.PMID 18582342
- [12]Bakr A, Silva D, Cramb R, et al. Outcomes of CSF spectrophotometry in cases of suspected subarachnoid haemorrhage with negative CT: two years retrospective review in a Birmingham hospital. British journal of neurosurgery, 2017.PMID 27931120
- [13]Cruickshank AM ACP Best Practice No 166: CSF spectrophotometry in the diagnosis of subarachnoid haemorrhage. Journal of clinical pathology, 2001.PMID 11684714
- [14]Basurto Ona X, Osorio D, Bonfill Cosp X Drug therapy for treating post-dural puncture headache. The Cochrane database of systematic reviews, 2015.PMID 26176166
- [15]Kannarkat GT, Darrow J, Moghekar A Reassessing accuracy of blood cell correction factor for traumatic lumbar puncture. Journal of the neurological sciences, 2022.PMID 34929498
- [16]Kozak M, Hallan DR, Stoltzfus M, et al. Lumbar Puncture in Thrombocytopenia: The Floor Is Not Firm. Cureus, 2023.PMID 37593278
- [17]Young N, Thomas M Meningitis in adults: diagnosis and management. Internal medicine journal, 2018.PMID 30387309