Developing a Decision Instrument to Guide Abdominal-pelvic CT Imaging of Blunt Trauma Patients

Unrecognized abdominal and pelvic injuries can result in catastrophic disability and death. Sporadic reports of "occult" injuries have generated concern, and physicians, fearing that they may miss such an injury, have adopted the practice of obtaining computed tomography on virtually all patients with significant blunt trauma. This practice exposes large numbers patients to dangerous radiation at considerable expense, while detecting injuries in a small minority of cases.

Existing data suggest that a limited number of criteria can reliably identify blunt injury victims who have "no risk" of abdominal or pelvic injuries, and hence no need for computed tomography (CT), without misidentifying any injured patient. It is estimated that nationwide implementation of such criteria could result in an annual reduction in radiographic charges of $75 million, and a significant decrease in radiation exposure and radiation induced malignancies.

This study seeks to determine whether "low risk" criteria can reliably identify patients who have sustained significant abdominal or pelvic injuries and safely decrease CT imaging of blunt trauma patients. This goal will be accomplished in the following manner:

All blunt trauma victims undergoing computed tomography of the abdomen/pelvis in the emergency department will undergo routine clinical evaluations prior to radiographic imaging. Based on these examinations, the presence or absence of specific clinical findings (i.e. abdominal/pelvic/flank pain, abdominal/pelvic/flank tenderness, bruising abrasions, distention, hip pain, hematuria, hypotension, tachycardia, low or falling hematocrit, intoxication, altered sensorium, distracting injury, positive FAST imaging, dangerous mechanism, abnormal x-ray imaging) will be recorded for each patient, as will the presence or absence of abdominal or pelvic injuries. The clinical findings will serve as potential imaging criteria. At the completion of the derivation portion of the study the criteria will be examined to find a subset that predicts injury with high sensitivity, while simultaneously excluding injury, and hence the need for imaging, in the remaining patients. These criteria will then be confirmed in a separate validation phase of the study.

The criteria will be considered to be reliable if the lower statistical confidence limit for the measured sensitivity exceeds 98.0%. Potential reductions in CT imaging will be estimated by determining the proportion of "low-risk" patients that do not have significant abdominal or pelvic injuries.