The Utility of Lumbar Puncture After a Negative Head CT in the Emergency Department Evaluation of Subarachnoid Hemorrhage.

American College of Emergency Physicians (ACEP) [1] recommends that patients presenting with acute non-traumatic headache concerning for subarachnoid hemorrhage (SAH) undergo lumbar puncture (LP) when non-contrast head computed tomography (CT) is negative. The diagnostic yield of this approach is unknown. Evaluate the diagnostic yield, lengths of stay and complication rates of LPs in patients undergoing Emergency Department (ED) evaluation for aneurysmal SAH.