Using computed tomographic imaging (CT scans) based only on a child’s method of injury in blunt trauma cases incurs more risks than benefits, according to a recent study.
The ionizing radiation from CT scanning has been linked to long-term risk of cancer, with an estimated risk of one cancer case per 10,000 CT scans, and the U.S. Environmental Protection Agency attributes 25% of all radiation in the United States to CT scanning.
"The benefit of identifying or excluding life-threatening injuries with a high sensitivity is an invaluable tool," wrote Dr. Hunter B. Moore and his colleagues at the University of Colorado at Denver, Aurora, in the Journal of Trauma and Acute Care Surgery. "However, application in the more radiosensitive pediatric population requires critical analysis."
Dr. Moore’s team found that the only clinically significant factor in determining the value of using CT scans was an abnormal Glasgow Coma Score (GCS). The GCS neurological scale rates patients from 3 to 14 on their level of consciousness; the highest score (14 on the original scale, 15 on the revised scale) refers to normal verbal, motor, and eye functioning. This study used the original scale, according to corresponding author Denis Bensard.
Dr. Hunter B. Moore
"Most concerning was that injured children imaged based on the mechanism of injury alone yielded no significant findings on CT imaging," the researchers wrote (J. Trauma Acute Care Surg. 2013;75:995-1001). "When anatomic or physiologic abnormalities were present, a serious CT finding was observed in more than 20% of the children imaged."
The researchers classified 174 patients, all meeting trauma team activation criteria at a Level 2 pediatric trauma center, into four groups to study the clinical value of CT scanning based on the children’s mechanism of injury. The patients, with a mean age of 7 years and a mean Injury Severity Score of 10, were admitted from January 2006 through December 2011.
The first group had normal GCS scores and normal vital signs and physical examinations. CT scanning for this group was considered to be done based on mechanism of injury alone. The second group had abnormal GCS scores but normal vital signs and physical exams. The third group had normal GCS scores but abnormal vital signs or exam findings. The fourth group had both abnormal GCS scores and abnormal findings in vital signs and/or exams.
Across all groups, motor vehicle collisions accounted for the most common injury causes, followed by being struck by autos as pedestrians, and falls. Positive CT scan findings included extra axial blood or parenchymal injury in the head; bony, vascular injury in the neck; great vessel injury in the chest; or solid organ or hollow visceral injury in the abdomen.
Of the 54 patients (82% of 66 children) in the group with normal exams, vital signs, and GCS scores who received CT scans, the patients were exposed to an average 17 mSv through an average 1.7 scans per child. The annual environmental dose limit for radiation is established at 1 mSv per year. "Remarkably, no patient imaged, based on [injury] mechanism alone, had a serious or life-threatening finding on CT scan," the researchers wrote.
All 25 patients in the group with abnormal GCS scores but normal exams and vital signs were scanned, with an average of 3.1 scans and 29 mSv of radiation per child. While 22% of the scans revealed a serious injury, the only surgeries required were one craniotomy and one nephrectomy.
Among the 57 children with normal GCS scores but abnormal exams or vital signs, 49 of them (86%) were scanned, with an average of two scans and 20 mSv per child. One splenectomy resulted from among the 23% of scans revealing significant findings.
All but 1 of the 26 children with abnormal GCS scores and abnormal vital signs or exams were scanned, with an average of 2.8 scans and 27 mSv per child. A quarter of the scans revealed significant findings, and two children required emergency craniotomies.
"We found that only one in four CT scans found a serious finding, but emergent operative interventions were required in less than 3% of injured children imaged," the researchers wrote. "Focused assessment with sonography for trauma [FAST] examination for the cohort was found to have a high specificity of 98%, but low sensitivity of 30%."
They determined the low sensitivity to result from the scans’ inability to identify injuries in solid organs without "detectable blood or retroperitoneal injury," though CT scans did appear valuable for identifying intra-abdominal hemorrhage. Abdominal CT scans were most likely to identify serious injuries when initial exams revealed anatomic or physiologic abnormalities, but chest scans had little to no utility.