Ottawa Subarachnoid Hemorrhage Rule
Ottawa Subarachnoid Hemorrhage Rule (Perry 2013) for alert patients with a new severe non-traumatic headache peaking within 1 hour.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Any exclusion present
- No
- Age >= 40
- Yes
- Neck pain or stiffness
- Yes
- Witnessed loss of consciousness
- No
- Onset during exertion
- No
- Thunderclap headache
- Yes
- Limited neck flexion on exam
- No
Result: Cannot rule out SAH by Ottawa SAH Rule: further workup indicated per Perry 2013 (100% sensitivity in the derivation cohort).
The tool opens with these values already filled in. Replace them with your own.
What the result means
- all negative
- Rule out SAH per Perry 2013 (100% sensitivity in the derivation cohort).
- any positive
- Cannot rule out SAH; further workup indicated per Perry 2013.
- exclusion present
- Ottawa SAH Rule does not apply per Perry 2013.
What you enter
- Any exclusion present (rule inapplicable)
- Age >= 40
- Neck pain or stiffness
- Witnessed loss of consciousness
- Onset during exertion
- Thunderclap headache (peak within 1 second)
- Limited neck flexion on exam
How this is calculated
Citation
Perry JJ, Stiell IG, Sivilotti MLA, et al. Clinical decision rules to rule out subarachnoid hemorrhage for acute headache. JAMA. 2013;310(12):1248-1255. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.