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
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.