Ottawa subarachnoid hemorrhage rule
Which patients with acute headache need investigation for subarachnoid hemorrhage.
Inputs
Age 40 or older
Neck pain or stiffness
Witnessed loss of consciousness
Onset during exertion
Thunderclap headache (instantly peaking pain)
Limited neck flexion on examination
Worked calculation
Your values are highlighted.
- Criteria present
When to use
- Alert patients 15 or older with new severe atraumatic headache peaking within 1 hour.
Pearls and pitfalls
- Not for prior aneurysm or SAH, known brain tumor, new neurologic deficits, or recurrent similar headaches.
- High sensitivity, low specificity.
Why use
Rules out SAH safely when all criteria are absent.
Positive if any criterion is present