On CT brain in a 22-year-old victim of assault, there is a biconvex hyperdense collection at the temporal region with a 'swirl sign' (mixed density). The swirl sign in acute intracranial haemorrhage indicates:
- A Chronic subdural haematoma with rebleed
- B Active ongoing haemorrhage with unclotted blood ✓
- C Calcification within the haematoma
- D Air within the haematoma indicating open fracture
Correct answer: B. Active ongoing haemorrhage with unclotted blood
Explanation
The swirl sign (heterogeneous low/isodense areas within a hyperdense haematoma) represents active ongoing haemorrhage where fresh unclotted blood mixes with clotted blood. It is a critical finding indicating rapid expansion and is associated with high mortality; it mandates urgent neurosurgical intervention. It is not chronic rebleed (which shows mixed density over different timeframes) nor calcification or pneumocephalus.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.