🧠 Fisher Grade (SAH CT)
UseWhen to use: admission SAH CT documentation and vasospasm-risk context.
StrataGrade 3 historically highest symptomatic vasospasm risk; Grade 4 differs from Mod. Fisher.
LimitsWhen not to use: as the only DCI prediction tool. · Pitfall: confusing classic Fisher with Modified Fisher IVH rules. · Pair with Modified Fisher and clinical monitoring.
SourceFisher CM et al. Neurosurgery 1980
This-shift next steps
After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.
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Methodology · worked example, guidelines & full notes
Grades 1–4.
When to use
When to use: admission SAH CT documentation and vasospasm-risk context.
How it works
1 no blood → 2 thin diffuse → 3 thick clots/layers ≥1 mm → 4 ICH/IVH pattern.
Key points
- Grades 1–4.
- Grade 3 highest classic risk.
- Next: Modified Fisher / Hunt-Hess.
References
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Admission CT appearance (classic Fisher) | Grade 2 — Diffuse thin SAH; vertical layers <1 mm; no clots |
|---|
→Fisher grade2/4
- Cue：Intermediate thin-diffuse pattern
- Related：Prefer Modified Fisher when IVH thickness matters
| Admission CT appearance (classic Fisher) | Grade 1 — No blood detected |
|---|
→Fisher grade1/4
- Cue：Lowest classic vasospasm association
- Related：Prefer Modified Fisher when IVH thickness matters
Verification & sources · governance
FAQ
Frequently asked questions
- Does Fisher Grade (SAH CT) upload patient data? Where is it calculated?
- Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
- How is Fisher Grade (SAH CT) calculated in practice? Can you show a worked example?
- Inputs: Admission CT appearance (classic Fisher) Grade 2 — Diffuse thin SAH; vertical layers <1 mm; no clots → Result: Fisher grade 2 /4（Cue: Intermediate thin-diffuse pattern, Related: Prefer Modified Fisher when IVH thickness matters） Inputs: Admission CT appearance (classic Fisher) Grade 1 — No blood detected → Result: Fisher grade 1 /4（Cue: Lowest classic vasospasm association, Related: Prefer Modified Fisher when IVH thickness matters）