For healthcare professionals
Modified Fisher scale
The modified Fisher scale grades a subarachnoid hemorrhage (bleeding around the brain) on the first CT scan from grade 0 to grade 4, using how thick the subarachnoid blood is and whether there is blood in the ventricles. This tool is written for clinicians reading the CT of a patient with a diagnosed bleed. It is not a self-check and not a diagnosis.
Initial CT findings
For a patient with a diagnosed subarachnoid hemorrhage, graded on the initial CT of the head. Nothing you enter leaves this page.
What you will see
The modified Fisher grade from 0 to 4 with its definition as printed in the source.
Educational only, not medical advice. A grade never replaces the judgment of the treating team.
Source
The modified Fisher scale by Frontera JA and colleagues, Neurosurgery 2006, with the grade definitions as printed in the open access Table 6 of Patel and colleagues, International Journal of Emergency Medicine 2021 (CC BY 4.0), and cross-checked against the Methods of Quintard and colleagues, Critical Care 2016 (CC BY 4.0). The tests check every grade against the printed wording.
Validated in
Patients with a subarachnoid hemorrhage, graded on the initial CT of the head. The original 2006 paper, which we cite but do not quote because its license does not allow reuse here, derived the scale to predict symptomatic vasospasm. Quintard and colleagues used it in 48 patients with an aneurysmal subarachnoid hemorrhage treated by coiling.
Limits
For a diagnosed subarachnoid hemorrhage only: the scale does not diagnose a bleed. The printed table does not define a numeric cut-off between thin and thick blood, so the choice rests on the reader of the CT. The table has no row for blood in the ventricles without subarachnoid blood, and this tool gives no grade in that case. Patel and colleagues print a vasospasm rate next to each grade, but the cross-check source does not, so this tool gives the grade only and no vasospasm estimate.
The grades
Modified Fisher scale, as printed in Patel and colleagues 2021, Table 6 (Patel 2021) (Frontera 2006):
- Grade 0: No SAH; no IVH
- Grade 1: Focal or diffuse, thin SAH; no IVH
- Grade 2: Thin, focal, or diffuse SAH; IVH
- Grade 3: Thick, focal, or diffuse SAH; no IVH
- Grade 4: Thick, focal, or diffuse SAH; IVH
Quintard and colleagues describe grades 1 to 4 the same way (Quintard 2016): grade 1 is focal or diffuse thin SAH with no IVH, grade 2 is focal or diffuse thin SAH with IVH, grade 3 is thick SAH with no IVH and grade 4 is thick SAH with IVH. They do not list a grade 0, and they add a grade 5 for IVH or intracerebral hematoma with clot, which is not in the Patel table (Quintard 2016). This tool follows the Patel table, grade 0 to 4.
Reading the result
Patel and colleagues write that the scale uses the initial CT to predict the incidence of vasospasm, that it was derived from the original Fisher grading scale to account for the thickness of the hemorrhage and any intraventricular hemorrhage, and that a higher grade means a higher incidence of vasospasm (Patel 2021). Quintard and colleagues note that the classification was proposed to assess the risk of vasospasm, not to assess prognosis directly (Quintard 2016). The grade describes the first scan only; it does not decide treatment on its own.
Related tools
To grade the clinical state of the same patient, use the Hunt and Hess scale or the WFNS grade. To decide which patients with a sudden severe headache need testing for a subarachnoid hemorrhage, see the Ottawa SAH rule. To score level of consciousness, use the Glasgow Coma Scale calculator. For a bleed into the brain tissue, see the ICH score. Other bedside scores are listed under For healthcare professionals.
Sources
- Patel S, Parikh A, Okorie ON. Subarachnoid hemorrhage in the emergency department. Int J Emerg Med. 2021;14(1):31. doi:10.1186/s12245-021-00353-w. PMID 33980142. Open access (CC BY 4.0). Table 6 (Modified Fisher Scale) and text. pmc.ncbi.nlm.nih.gov/articles/PMC8117305/
- Quintard H, Leduc S, Ferrari P, Petit I, Ichai C. Early and persistent high level of PS 100β is associated with increased poor neurological outcome in patients with SAH: is there a PS 100β threshold for SAH prognosis? Crit Care. 2016;20:33. doi:10.1186/s13054-016-1200-1. PMID 26843206. Open access (CC BY 4.0). Background and Methods (modified Fisher grade list). pmc.ncbi.nlm.nih.gov/articles/PMC4738799/
- Frontera JA, Claassen J, Schmidt JM, Wartenberg KE, Temes R, Connolly ES Jr, MacDonald RL, Mayer SA. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified Fisher scale. Neurosurgery. 2006;59(1):21-27. doi:10.1227/01.NEU.0000218821.34014.1B. PMID 16823296. Original grading (cited, not quoted). doi.org/10.1227/01.NEU.0000218821.34014.1B
- Centers for Disease Control and Prevention. Signs and Symptoms of Stroke. www.cdc.gov/stroke/signs-symptoms/index.html
Written and maintained by the uncovermyrisk.com editorial team. We do not have a medical reviewer; every claim links to its primary source above. Last reviewed: 2026-11-03. Spotted an error? See About.