Rate and Reasons for Repeat CT Scanning in Transferred Trauma Patients.

To describe the reasons and additional radiation for CT scans repeated after transfer to a trauma center. Retrospective study of patients transferred to a trauma center. Patients had repeat CT if a CT of the same region was repeated at the trauma center's emergency department. Indications for repeat CT scanning were abstracted. Radiation dosage was calculated in millisieverts. A total of 370 had CT scans and were transferred. Mean age was 39.1 ± 28.0 years. Seventy-four [20.0%, 95% confidence interval (CI) 16.0-24.4%] had 103 CTs repeated. Adults (64/254, 25.2%) were more likely than children (10/116, 8.6%) to undergo repeat CT (difference 16.6%, 95% CI 9.2-24.0%). Types of CTs repeated included: head 48 (47%), face 6 (6%), cervical spine/neck 21 (20%), thoracolumbar spine 4 (4%), chest 4 (4%), and abdominal/pelvic 20 (19%). Reasons for repeat CT were outside CT unavailable 31 (42%), insufficient image quality/additional details needed 15 (20%), disease progression 16 (22%), unknown 10 (14%), and consult request unknown reason 2 (3%). Median dose for the repeat CT scans was 4.19 mSv (interquartile range 1.98, 6.28) and was 4.79 mSv (interquartile range 2.47, 8.22) when the CTs were unavailable. Effective dose of the repeat scans was greater than 10 mSv in 13 (3.5%) patients. Patients transferred to a trauma center often undergo repeat CT. The most common reason for repeated imaging was failure to transport original CT scans with the patient or images that were unable to be viewed. Trauma centers should work with their catchment areas to establish systems that ensure transfer of all radiographic imaging.