Head CT Without Contrast is the Primary Study to Order
For a patient who fell and hit their head, order a noncontrast head CT if they meet specific clinical criteria based on the 2008 ACEP Clinical Policy, which provides the most practical framework for decision-making 1.
Decision Algorithm for Imaging
If Patient Had Loss of Consciousness (LOC) or Post-Traumatic Amnesia (PTA):
Order noncontrast head CT if ANY of the following are present (Level A recommendation):
- Headache
- Vomiting
- Age >60 years
- Drug or alcohol intoxication
- Deficits in short-term memory
- Physical evidence of trauma above the clavicle
- Post-traumatic seizure
- GCS score <15
- Focal neurologic deficit
- Coagulopathy (anticoagulants or antiplatelet agents)
If Patient Had NO Loss of Consciousness or Amnesia:
Consider noncontrast head CT if ANY of the following are present (Level B recommendation):
- Focal neurologic deficit
- Vomiting
- Severe headache
- Age ≥65 years
- Physical signs of basilar skull fracture
- GCS score <15
- Coagulopathy
- Dangerous mechanism of injury (ejection from vehicle, pedestrian struck, fall from >3 feet or 5 stairs)
Critical Context and Pitfalls
The mechanism matters significantly. While guidelines list "fall" as a potential indication, the biomechanical force is crucial. Falls from standing height or minor impacts (like hitting a shelf while standing) carry extremely low risk—one study of 109 patients who hit their heads on cupboards/shelves without falling found zero cases of intracranial pathology despite 72% meeting NICE criteria 2. Context-aware application of decision rules prevents unnecessary imaging.
Age and anticoagulation lower the threshold substantially. In older adults (≥65 years), approximately 49% receive cranial CT after falls, but the yield remains low—only 4.9% show intracranial hemorrhage and <1% require neurosurgical intervention 3. However, the consequences of missing a bleed in anticoagulated patients are severe, justifying the lower threshold 1.
Unwitnessed falls create diagnostic uncertainty. When history is unclear (common in 71% of older adult falls), clinicians often default to imaging 3. In these cases, focus on objective findings: reduced GCS, seizure, or new neurological signs are more predictive of intracranial hemorrhage than unclear history alone 3.
What NOT to Order Initially
- MRI, MRA, CTA, PET, SPECT, or skull radiographs have no role in initial evaluation 1
- Skull X-rays are obsolete—CT is far more sensitive for neurosurgical lesions 1
- Advanced imaging is reserved for specific scenarios (suspected vascular injury, persistent deficits after negative CT)
Laboratory Studies
While the guidelines focus on imaging, check coagulation studies (PT/INR, aPTT) if the patient is on anticoagulants, as this directly affects both imaging decisions and management. The evidence emphasizes coagulopathy as a key risk factor but doesn't mandate routine labs in all head trauma patients 1.
When Imaging is NOT Needed
If the patient has GCS 15, no LOC/PTA, and none of the risk factors listed above, imaging is usually not appropriate 1. This applies to the majority of mild head trauma cases—over 75% have GCS 15, and only 10% of those imaged show any findings, with <1% requiring neurosurgical intervention 1.
Follow-Up Imaging Considerations
If initial CT is positive (e.g., subdural hematoma), repeat CT is appropriate for neurologic deterioration but routine repeat imaging may not be needed if the patient remains stable with small hemorrhages (<10 mL) and normal neurologic exam 1. The risk of delayed hemorrhage after negative initial CT is very low (<0.5%), even in anticoagulated patients 1.