BACKGROUND: Swirl sign has previously been described in epidural hematomas as 
areas of low attenuation, radiolucency or irregular density. The aims of this 
study were to describe swirl sign in ICH, study its prevalence, study the 
reliability of the subjective evaluation on computed tomography (CT), and to 
explore its prognostic value.
METHODS: CTs of 203 patients with ICH were retrospectively evaluated for the 
presence of swirl sign. Association between swirl sign and different clinical 
and radiological variables was studied.
RESULTS: Inter- and intraobserver agreement with regard to the occurrence of 
swirl sign was substantial (К 0.80) and almost perfect (К 0.87), respectively. 
Swirl sign was found in 30% of the study population. 61% of patients with swirl 
sign were dead at one month compared with 21% of those with no swirl sign (p < 
0.001). Only 19% of patients with swirl sign exhibited favorable outcome at 
three months compared with 53% of those with no swirl sign (p < 0.001). Patients 
with swirl sign exhibited larger ICHs with average ICH-volume 52 ± 50 ml (median 
42 ml) compared with 15 ± 25 ml (median 6) in patients whose CT did not show 
swirl sign (p < 0.001). Swirl sign was independent predictor of death at one 
month (p = 0.03; adjusted odds ratio 2.6, 95% CI 1.1 - 6), and functional 
outcome at three months (p = 0.045; adjusted odds ratio 2.6, 95% CI 1.02 - 6.5).
CONCLUSIONS: As swirl sign showed to be an ominous sign, we recommend 
identification of this sign in cases of ICHs.