Introduction The aim of this study was to determine the Relative Risk (RR) ratios for common clinical correlates in adult patients with minor head injury in a cohort of patients in which loss of consciousness (LOC) and post-traumatic amnesia (PTA) were not the only entry criteria for CT scanning.

Methods The computerised CT request notes were reviewed on all patients who underwent a CT head scan with a minor head injury over a 1-year period (January 2009–December 2009). The clinical signs and symptoms at presentation were extracted from the request notes and the RR ratios were calculated for five clinical correlates: LOC, PTA, vomiting, nausea and headache.

Results 456 Glasgow coma scale (GCS) 15 patients underwent CT scanning during the period January 2009–December 2009. 55 of the 456 patients had positive CT findings (12%). 270 patients (59%) of the GCS 15 cohort had neither LOC nor PTA and of this subgroup 27 had positive scans. LOC was the only clinical correlate in which the RR reached statistical significance; RR 2.0930 (95% CI 1.25 to 3.50). However, vomiting accounted for four cases, headache for four cases and nausea for no cases.

Conclusions Using LOC or PTA as the principal entry criterion for CT scanning may result in a significant number of patients with traumatic intracranial injury being missed. Using a less stringent approach still achieved an acceptable CT abnormality rate.