Fisher Grade Calculator

Fisher Grade Calculator for Neurology. Classic grade 3 had the strongest historical vasospasm association; the ordering is not a linear risk ladder. Contemporary SAH management needs the broader clinical assessment: https://www.ahajournals.org/doi/10.1161/STR.0000000000000436

For shared guidance on choosing a tool and documenting results, read the clinical calculator workflow.

How this calculator works

Assign the classic CT pattern, grades 1-4. The original report is https://pubmed.ncbi.nlm.nih.gov/7354892/ . The AANN source table confirms the >=1 mm boundary and grade-4 distribution: https://aann.org/uploads/AANN_Aneurysmal_Subarachnoid_Hemorrhage.pdf

When to use this calculator

Describe the initial CT blood burden in aneurysmal SAH. Explicitly state classic Fisher so the result is not confused with modified Fisher.

Inputs used

  • CT assessed in aneurysmal SAH
  • Radiologically determined classic blood-distribution category, including thin/thick SAH and intracerebral/intraventricular clot

Clinical interpretation

Classic grade 3 had the strongest historical vasospasm association; the ordering is not a linear risk ladder. Contemporary SAH management needs the broader clinical assessment: https://www.ahajournals.org/doi/10.1161/STR.0000000000000436

Worked example

A localized subarachnoid clot, or a vertical SAH layer exactly 1 mm thick, fits grade 3. Grade 4 instead describes intracerebral or intraventricular clot with thin diffuse or absent SAH.

Limitations and safety notes

CT timing, resolution and blood-pattern interpretation matter. The widget does not infer a grade from images, compute a modified Fisher grade, or output a personal vasospasm probability. Uncertain patterns remain unclassified.

Frequently asked questions

Does any intraventricular blood automatically mean grade 4?

No. The classic grade-4 definition also specifies diffuse thin or absent subarachnoid blood. Do not import the modified Fisher combinations.

References

  • Fisher et al. Original CT blood grouping, 1980: https://pubmed.ncbi.nlm.nih.gov/7354892/
  • AANN aneurysmal SAH guideline; classic Fisher table and clinical context: https://aann.org/uploads/AANN_Aneurysmal_Subarachnoid_Hemorrhage.pdf
  • AHA/ASA aneurysmal SAH guideline, 2023: https://www.ahajournals.org/doi/10.1161/STR.0000000000000436

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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