SAN DIEGO – Children who have suffered blunt trauma are routinely screened in emergency departments for intra-abdominal injury via computed tomography of the abdomen and pelvis.
But concerns about excess exposure to CT radiation, particularly to the gonads, led one group of researchers to question whether it’s necessary to scan the entire abdominopelvic region in all of these patients to identify intra-abdominal injury (IAI).
Dr. Stacy Reynolds
Dr. Stacy Reynolds and her colleagues at the Carolinas Medical Center in Charlotte, N.C., hypothesized that CT limited to the radiographic abdomen – the region between the dome of the diaphragm to the top of the iliac crest – can capture the vast majority of IAIs in this population.
At the Society for Academic Emergency Medicine annual meeting, Dr. Reynolds presented results from a retrospective cohort study enrolling 313 hemodynamically stable pediatric patients (median age 14 years, 64% male) presenting to 12 EDs after blunt trauma. Patients with known pelvic fractures or hip dislocation were excluded, as they would have had a clear indication for a full abdominopelvic CT.
All subjects underwent axial abdominopelvic CT imaging. Researchers created matched pairs of images comprising the original scans and those that had been altered with software that truncated the pelvic portion of the study to create CT abdomen-only studies. Study radiologists were blinded to the results of the original scans.
Twenty-six IAI’s were diagnosed in 24 patients: 8 hepatic injuries, 12 splenic injuries, 5 renal injuries, and 1 retroperitoneal hemorrhage. Abdominal CT alone was 85% sensitive (95% confidence interval, 65%-96%) and 99% specific (95% CI, 97%-100%) in identifying IAIs. The four missed injuries were solid organ injuries within the radiographic abdomen. False positives occurred in two of the complete scans, both involving free fluid prompting suspicion of small bowel injury later ruled out by clinical observation.
Dr. Reynolds said in an interview said that the findings, while promising, were limited by the study’s small numbers, and its use of axial images alone, when sagittal images also would be required for the most accurate diagnoses. Also, physician suspicion of IAI prior to imaging was not captured because of the study’s retrospective design, she said. “The real key to whether or not this hypothesis is valuable is if physicians are able to target the right population of patients for application.”
Dr. Reynolds cautioned that the findings would need to be validated in a larger trial before any changes could be made to clinical practice. “Some of the outcomes that we need to make sure whether we’re missing are still rare,” she said. “You couldn’t feel confident that this is the right way to go with a study this small, but it establishes that we can safely and ethically pursue a multicenter trial that would examine the issue with bigger numbers.”
Other groups of investigators, including members of the Pediatric Emergency Care Applied Research Network (PECARN), also have taken up the question of identifying children at low risk of IAI who may not need CT screening after blunt trauma. In 2013, PECARN published a prediction rule using only patient history and physical examination findings intended to obviate use of CT in the lowest-risk patients (Ann. Emerg. Med. 2013;62:107-16.e2).
Dr. Reynolds said that while overuse of CT was a worrisome trend that could have long-term implications for patients, and that it was important to identify ways it might be limited, there is a reason it remains the go-to technology in the ED for detecting IAI. “It’s got very high sensitivity and specificity. If you’re a busy trauma surgeon who’s admitting 20 injured patients in a night, there’s no faster or more efficient way to determine whether the patient in front of you is injured.”
The study was funded by the Carolinas Trauma Network Research Center of Excellence. None of the investigators disclosed conflicts of interest.