Acute Subdural Hematoma Detection

Imaging Characteristics

The American College of Radiology recommends that non-contrast computed tomography (CT) scans can detect acute subdural hematomas with 100% sensitivity from the moment of formation, making it the gold standard for diagnosis of acute hemorrhage due to its availability, speed, and high diagnostic accuracy 1, 3
The American Heart Association notes that the hematoma appears as a hyperdense collection (60-80 Hounsfield units) in the first 24-72 hours after trauma, making it easily visible on initial CT scans 2

The American College of Emergency Physicians states that CT angiography (CTA) can detect active contrast extravasation within the subdural hematoma, indicating active bleeding and high risk of expansion, which is visible immediately during the study 1
The American Association of Neurological Surgeons recommends that a follow-up CT scan be performed at 6 and 24 hours in neurologically stable patients to rule out hematoma expansion, as expansion occurs in 26% of patients within the first hour and in an additional 12% by 20 hours 3, 4

The American College of Radiology recommends that non-contrast CT is the first-line modality and should be performed emergently in all patients with suspected acute subdural hematoma 1, 2
The American Heart Association notes that magnetic resonance imaging (MRI) with gradient-echo sequences is equally sensitive to CT for detecting acute bleeding, but is not practical in the emergency context due to contraindications, acquisition time, and limited availability 1, 5
The American College of Chest Physicians states that in anticoagulated patients, a follow-up CT scan is required at 24 hours even if the initial CT is negative, due to the risk of late bleeding (1.4-4.5%) 4