Repeat CT scan in closed head injury.

Background: Cranial CT scans are often repeated to observe the progress of an intracranial injury. This prospective observational study analyses the effect of repeat CT scans with the aim of formulating a guideline for their use.

Methods: One hundred and seventy-five patients with blunt head injury presenting to the trauma unit and undergoing CT scan were included. Unstable patients with polytrauma were excluded. There was no standard protocol for ordering the repeat cranial CT scans. This decision was purely based on the discretion of neurosurgeons.

Results: CT scan was repeated in 53 (30%) patients. The clinical indications for the repeat CT scan could be grouped into three: (i) clinical deterioration, (ii) failure of improvement, and (iii) as a follow-up scan. Nine underwent surgical intervention based on the repeat CT scan findings. They were associated with clinical deterioration and had a better survival after surgery. In others the repeat CT scan findings did not alter the management.

Conclusion: When a head injured patient shows clinical deterioration, it is necessary to repeat the CT scan to pick up a surgically treatable lesion; which is likely in a significant number of patients. Repeat CT scan as a matter of "routine" follow-up when the patient is clinically status-quo or improving, is unlikely to yield any further information necessitating change in treatment. This guideline may be useful in settings where CT scan facility is not easily available or expenditure is an issue.