Urgent and out-of-hours CT Brain for subarachnoid haemorrhage and subsequent Lumbar Puncture


Urgent and out-of-hours CT brain undertaken to identify subarachnoid haemorrhage (SAH) or contra-indications to subsequent lumbar puncture (LP).  


A significant number of urgent or out-of-hours requests for CT brain are made to identify a visible SAH.  Normal CT brain examinations then usually require LP. This is dependent on a normal CT scan.  All current national guidance requires a LP following a normal CT brain (Ref.1-7).  This should be carried out with a degree of clinical urgency but should not be performed within 12 hours of onset of headache. 

The Cycle

The Standard

In all cases where patients undergo urgent or out-of-hours CT as a prerequisite for proceeding to a LP, if CT does not reveal either a contraindication to LP or any finding rendering LP unnecessary, then an LP should be performed no sooner than 12 hours from the onset of symptoms ( Ref 8, 11, 13.)



Assess local practice


• Cases in which patients undergo urgent or out-of-hours CT for SAH as a prerequisite for proceeding to an LP and the CT does not reveal either a contraindication to LP, or any finding rendering LP unnecessary

• Percentage who actually undergo the LP and have the LP results available no sooner than 12 hours from headache onset.

Data items to be collected

For each patient:

• Whether appropriate clinical details are included in the request (e.g. timing of headache onset, sign of raised intracranial pressure, GCS, focal neurological deficits)

• The time of the CT examination

• Whether a SAH is demonstrated

• Whether the CT reveals a contraindication to LP

• If and when the LP was performed

• The result of the report on the LP

• The result and time of the report on the LP

Suggested number

40 consecutive requests.

Suggestions for change if target not met

• Discuss the audit results with radiologists and clinical referring teams

• Reinforce the local guidelines for CT urgent requests

• Clinicians must be aware that a normal CT does not exclude raised intra-cranial pressure and clinical findings need also to be taken into account

• Agree with clinicians that only a consultant or a specialist registrar at year 3 or higher can request an urgent CT scan in these circumstances


- Review of request forms

- Review of patients’ notes / discharge letters

- Review of laboratory log books

- Radiologist (8 hours)


  1. Diagnosis and management of headache in adults. SIGN Guidelines 107. Health Improvement Scotland, 2008.

  2. National Institute for Health and Clinical Excellence (2008) Stroke and transient ischaemic attack in over 16s: diagnosis and initial management. NICE Guideline (CG68).

  3. Intercollegiate Stroke Working Party. National clinical guideline for stroke, 4th edition. London: Royal College of Physicians Physicians, 2012.

  4. Vivancos J, et al. Clinical management guidelines for subarachnoid haemorrhage. Diagnosis and treatment.  Neurologia. 2014;29:353–70.

  5. Steiner T, Juvela S, Unterberg A, et al. European Stroke Organization guidelines for the management of intracranial aneurysms and subarachnoid haemorrhage. Cerebrovasc Dis 2013;35:93–112

  6. Connolly. ES, et al. Guidelines for the management of aneurysmal subarachnoid hemorrhage: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke 2012;43:1711–37

  7. Lansley, J., et al. Subarachnoid haemorrhage guidelines and clinical practice: a cross-sectional study of emergency department consultants' and neurospecialists' views and risk tolerances.  BMJ Open. 2016; 6: e012357.

  8. Brown, S.C., et al. Investigating suspected subarachnoid haemorrhage in adults.  BMJ.  2011; 342:d2644.

  9. Cooper, J.R., Routine use of CT prior to lumbar puncture.  Br J Radiol. 1999;72: 885(319).

  10. Moss JG, Murchison JT. Is Radiology a nine to five specialty? Clin Radiol 1992;46:124–7.

  11. Greig, P., Goroszeniuk, D. Role of computed tomography before lumbar puncture: a survey of clinical practice. Postgrad Med J 2006; 82:162-165. 

  12. Hasbun, R., et al., Computed tomography of the head before lumbar puncture in adults with suspected meningitis.  N Engl J Med. 2001; 13:345(24)

  13. Perry, JJ. et al. Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study.  BMJ 2011;343:d4277

  14. Backes, D., et al. Time-Dependent Test Characteristics of Head Computed Tomography in Patients Suspected of Nontraumatic Subarachnoid Hemorrhage.  Stroke. 2012; 43:2115-2119.

Editors Comments

Submitted by

Taken from Clinical Audit in Radiology 100+ recipes RCR 1996, updated by B Morrissey & L Narayanan

Co Authors

Published Date

Monday 7 January 2008