Ultrasound, CT Comparable to Detect Appendicitis in Children

Laurie Barclay, MD

December 05, 2013

Using ultrasound as the first diagnostic imaging technique to detect appendicitis in children produces comparable outcomes to computed tomography (CT) scanning with less radiation and without increasing hospital length of stay, according to a retrospective study published in the December issue of the American Journal of Roentgenology.

"As more people become aware of the risks of medical radiation, there are increasing efforts to utilize non-radiation emitting imaging techniques as a first approach to diagnosis," second author Jessica Kurian, MD, attending radiologist, Division of Pediatric Radiology, the Children's Hospital at Montefiore and assistant professor, Albert Einstein College of Medicine of Yeshiva University in New York City, said in a news release. "Our research shows that using ultrasound first in the evaluation of appendicitis commonly produces actionable results and should be considered more frequently as clinicians try to limit medical radiation exposure in children."

Appendicitis is one of the prevalent conditions among US children, and the incidence is increasing. Although CT is the most frequently used imaging technique to assess patients with symptoms suggesting appendicitis, it is associated with significant radiation exposure. In contrast, ultrasound causes no radiation exposure.

The study goal was to determine whether the rate of complicated appendicitis and the hospital length of stay (LOS) increased during the transition to a protocol of using ultrasound first for the imaging workup of acute appendicitis in children.

To identify pediatric patients with surgically proven appendicitis from 2005 to 2011, the investigators searched the hospital billing database for discharge diagnosis codes for simple appendicitis (International Classification of Diseases, 9th Revision [ICD-9], code 540.9) and complicated appendicitis (ICD-9 codes 540.0 and 540.1).

They evaluated and plotted annual trends for the study period of the percentages of these patients who underwent ultrasound and CT. Using the Spearman (ρ) rank correlation test, they examined correlation of complicated appendicitis and median hospital LOS with calendar year.

Ultrasound Use Increased During the Study

Among 804 patients who met inclusion criteria, there was a moderate downward association of percentage of patients undergoing CT with year (ρ, −0.32; P < .01) and a moderate upward trend in the percentage of patients who first had ultrasound (ρ, 0.44; P < .01).

During the 7-year study period, the percentage of patients who had only ultrasound imaging before appendectomy increased moderately (ρ, 0.33; P < .01).

As collaboration between radiologists and clinicians in pediatric surgery and emergency medicine increased, however, use of ultrasound as the first imaging test also increased, going from 33% at the beginning of the study to nearly 90% at study end. In contrast, use of CT scan as the first and only diagnostic test decreased from 43% to less than 10%.

During the study, there was no significant increase in the proportion of patients with complicated appendicitis (ρ, −0.01; P = .74) or in the median hospital LOS (ρ, −0.04; P = .25).

Limitations of this study include a retrospective design, few data about why specific tests were or were not performed in specific patients, inclusion of only the patients who had proven appendicitis rather than all the patients who presented with suspected appendicitis, and possible confounding.

Ultrasound First Safely Limits Radiation Exposure

"Our study, which took place during Montefiore's transition to an 'ultrasound-first' model, shows that the percentage of patients who received ultrasound first significantly increased without impacting the median hospital [LOS], which remained consistent," Dr. Kurian said. "These findings support the use of ultrasound in helping to reduce radiation exposure in kids and suggest this approach could be applied in the diagnosis of other conditions to minimize the cumulative radiation dose a child is exposed to over the course of a lifetime."

At the authors' institution, education about alternate testing options, such as ultrasound and magnetic resonance imaging, has recently led to a dramatic decrease in the number of CTs done on pediatric patients. Strategies include educational seminars regarding the appropriate radiation dose, reinforcement of "ALARA" ("as low as reasonably achievable"), encouraging technologists to use appropriate dosage, and distributing awareness materials regarding the potential risks and benefits of various imaging modalities.

The National Center for Research Resources, a component of the National Institutes of Health (NIH), and NIH Roadmap for Medical Research supported this study in part. The authors have disclosed no relevant financial relationships.

Am J Roentgenol. 2013;201:1348-1352. Abstract

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