How should I approach the investigation of a suspected subdural haemat

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Approach to investigating suspected subdural haematoma in a patient with head trauma:

Perform an urgent CT head scan as the primary investigation to detect acute clinically important traumatic brain injury, including subdural haematoma, in any patient with a history of head trauma and clinical suspicion .
Use clinical decision rules to identify patients who require CT imaging promptly, such as those with loss of consciousness, abnormal drowsiness, persistent vomiting, amnesia, or on anticoagulant/antiplatelet therapy .
Ensure CT imaging is done within 1 hour for patients under 16 with multiple risk factors or within 8 hours for adults on anticoagulants, or sooner if presenting late after injury .
Do not use MRI as the primary investigation for acute traumatic brain injury due to safety and logistic reasons, but it may provide additional prognostic information .
Do not use plain skull X-rays to diagnose traumatic brain injury before consulting a neuroscience unit .
After imaging, if new and surgically significant abnormalities such as subdural haematoma are identified, discuss the case urgently with a neurosurgeon for management planning .
Admit patients with clinically important abnormalities on imaging or with persistent neurological symptoms for observation and specialist care .

How should I approach the investigation of a suspected subdural haematoma in a patient with a history of head trauma?