Letters

Subarachnoid haemorrhage: lumbar puncture for every negative scan? Authors' reply

BMJ 2006; 333 doi: http://dx.doi.org/10.1136/bmj.333.7567.550-a (Published 07 September 2006) Cite this as: BMJ 2006;333:550
  1. Rustam Al-Shahi, MRC clinician scientist ([email protected]),
  2. Philip M White, consultant neuroradiologist,
  3. Richard J Davenport, consultant neurologist,
  4. Kenneth W Lindsay, consultant neurosurgeon
  1. Division of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU
  2. Division of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU
  3. Institute of Neurological Sciences, Southern General Hospital, Glasgow G51 4TF

    EDITOR—Coats suggests that a lumbar puncture should not be undertaken after a negative computed tomogram for every patient with “query subarachnoid haemorrhage.”1 We robustly disagree.

    Firstly, in his bayesian calculations, Coats used the sensitivity of computed tomography for identifying subarachnoid blood at 12 hours after onset of headache (98%). Sensitivity decays rapidly within days, so patients who do not present immediately, or who have to wait for computed tomography, are less likely to be identified, and the importance of a subsequent lumbar puncture cannot be overstated. Furthermore, computed tomography is …

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