The Swirl Sign: Radiology Essentials
1. Clinical Definition
The Swirl Sign refers to the appearance of non-clotted, lower-density blood (serum) swirling within a higher-density, coagulated hematoma on a non-contrast CT scan.
2. High-Yield Significance
- Pathophysiology: Indicates active bleeding or hematoma expansion within the brain. The density difference is due to the varying concentrations of hemoglobin and serum as the clot matures.
- Prognostic Value: It is a poor prognostic indicator, frequently associated with neurological deterioration and increased risk of re-bleeding in cases of acute intracranial hemorrhage.
3. Imaging Context
| Feature | Clinical Implication |
|---|---|
| Presence | Suggests an unstable hematoma; closely monitor for expansion. |
| Location | Most commonly described in acute subdural hematomas (SDH) or intraparenchymal hemorrhages (IPH). |
4. Examination Pearls
- Distinction: Must be differentiated from fluid-level hematomas, which usually indicate coagulopathy or the use of anticoagulants.
- Management: Often prompts urgent neurosurgical consultation or aggressive correction of any underlying coagulopathy.