Although research supports ultrasound as the initial imaging tool in the evaluation of pediatric patients with suspected appendicitis, physicians in general emergency departments continued to rely on CT and use of CT grew from 1999 to 2007, according to a study published online April 24 in Radiology.

The findings point to the need for strong appropriateness and imaging use guidelines, the researchers said. Anastasia L. Hryhorczuk, MD, from the department of radiology at Children’s Hospital Boston, and colleagues noted the diagnostic challenges of evaluating children with nontraumatic abdominal pain, with concern for possible appendicitis instigating diagnostic imaging.

Although CT provides rapid and accurate diagnoses of appendicitis, “recent enthusiasm for CT has been tempered because of widespread public concern about the potential risks of radiation exposure,” wrote the study authors. Research has demonstrated the utility of a staggered imaging model, beginning with ultrasound and proceeding to CT in cases of negative or equivocal findings.

Whether or not these findings have been employed in practice remained uncertain. Thus, Hryhorczuk and colleagues devised a study to determine national trends in imaging use among children presenting to EDs with nontraumatic abdominal pain.

The researchers examined data from the National Hospital Ambulatory Medical Care Survey to evaluate imaging utilization among children with acute abdominal pain in U.S. emergency departments and reported 16,900,000 pediatric ED visits for nontraumatic abdominal pain from 1999 to 2007.

CT increased from 2 percent in 1999 to 16 percent in 2007 among patients younger than 20 with abdominal pain, according to Hryhorczuk et al. However, use of ultrasound did not significantly increase during the study period.

The researchers reported disparities in imaging use across the U.S. and indicated it appears to be influenced by sex, age, race and insurance status. Statistical analysis demonstrated increased odds of CT use in teens, white patients, the Midwest region, urban settings, patients with private insurance and patients who were admitted or transferred.

Although the study did not investigate reasons for these variations, Hryhorczuk and her colleagues pointed out that CT scanners are readily available in hospitals, whereas access to ultrasound may be limited based on operator availability in some areas. The local legal climate also may play a factor in obtaining imaging exams, according to the study, as appendicitis diagnoses are a source of lawsuits in the pediatric emergency setting.

The researchers described discrepancies between published guidelines and practice, specifically related to initial use of ultrasound for evaluation of suspected appendicitis. “The odds of CT are significantly increased in patients with appendicitis, whereas the odds of ultrasound are not.” Among patients ultimately diagnosed with appendicitis, 11 percent underwent ultrasound, 39 percent underwent CT and 3 percent underwent both exams.

CT use was reduced among patients with public insurance and with alternate nonprivate forms of insurance and those paying out of pocket. However, prior studies have suggested this population is at higher risk for perforated appendicitis. “Given that CT serves an important role in the imaging of complicated appendicitis and the evaluation of abscess formation, it is surprising that CT use is reduced in this population, for whom a higher rate of complications is expected,” wrote Hryhorczuk and colleagues.

Another important finding was related to differences in protocols between pediatric-focused and general EDs. Patients at pediatric EDs were more than 25 percent less likely to undergo CT even after adjustment for other characteristics. The researchers hypothesized that clinicians at pediatric facilities may employ skill sets and experience that provide care without imaging. “Focusing quality improvement initiatives on physicians at general hospitals may be an effective approach to decrease rates of CT imaging in pediatric patients,” the researchers wrote.