How accurate are CT scans in detecting subarachnoid hemorrhage?

January 01, 0001

How accurate are CT scans in detecting subarachnoid hemorrhage?

Sudden onset of severe headache can be a sign of subarachnoid hemorrhage. These Canadian researchers examined modern computed tomography in cases of possible subarachnoid hemorrhage. They performed a prospective cohort study based in tertiary care emergency departments, enrolling neurologically intact adults with headache clinically suggestive of subarachnoid hemorrhage (new, acute, peak less than one hour from onset)

The researchers found: "Of the 3132 patients enrolled (mean age 45.1, 2571 (82.1%) with worst headache ever), 240 had subarachnoid haemorrhage (7.7%). The sensitivity of computed tomography overall for subarachnoid haemorrhage was 92.9%, the specificity was 100%, the negative predictive value was 99.4%, and the positive predictive value was 100%. For the 953 patients scanned within six hours of headache onset, all 121 patients with subarachnoid haemorrhage were identified by computed tomography, yielding a sensitivity of 100%, specificity of 100%, negative predictive value of 100%, and positive predictive value of 100%."

The researchers concluded: "Modern third generation computed tomography is extremely sensitive in identifying subarachnoid haemorrhage when it is carried out within six hours of headache onset and interpreted by a qualified radiologist."

Modern CT scans are quite accurate in detecting subarachnoid hemorrhage, especially if done during the first six hours of symptoms

For the full abstract, click here.

BMJ 343:d4277, 18 July 2011 © 2011 BMJ Publishing Group Ltd.
Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study. Jeffrey J Perry, Ian G Stiell, Marco L A Sivilotti, et al. Correspondence to J J Perry: [email protected]

Category: N. Neurological. Keywords: subarachnoid hemorrhage, headache, thunderclap, diagnosis, CT scan, prospective cohort study, journal watch.
Synopsis edited by Dr Paul Schaefer, Toledo, Ohio. Posted on Global Family Doctor 9 August 2011

Pearls are an independent product of the Cochrane primary care group and are meant for educational use and not to guide clinical care.

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