Subarachnoid hemorrhage (SAH) is an important but uncommon condition in the differential diagnosis of acute headache. Most authorities recommend that patients with suspected SAH undergo noncontrast computed tomography (CT) as a first diagnostic intervention. If the results of the CT scan are negative, a lumbar puncture should be performed. Many nonurban Canadian hospitals do not have CT scanners and must either transfer patients or consider performing lumbar puncture prior to CT. In selected patients, performing lumbar puncture first may be an option, but timing of the procedure and the interpretation of results is important.
