Trends in Use of Diagnostic Imaging for Abdominal Pain in U.S. Emergency Departments.

CT has excellent accuracy for appendicitis but is associated with risks. Research and educational campaigns have been conducted to implement an ultrasound-first strategy for children but not for adults. The purpose of this study was to measure the use of CT and ultrasound in emergency department (ED) visits for abdominal pain and appendicitis to examine the impact of these efforts. We analyzed data from the National Hospital Ambulatory Medical Care Survey (1997-2016). Use of CT and ultrasound was measured over time in visits for abdominal pain and visits in which appendicitis was diagnosed. Predictors of CT use were identified by means of regression analysis. For children, CT use increased from 1.2% (95% CI, 0.6-2.5%) in 1997, peaked in 2010 at 16.6% (95% CI, 13.8-19.6%), and decreased slightly in 2016. In adults, CT use increased steadily from 3.9% in 1997 (95% CI, 3.1-4.8%) to 37.8% (95% CI, 35.5-41.0%) in 2016. CT use increased for both pediatric and adult ED visits with a diagnosis of appendicitis, from 5.2% (95% CI, 0.7-29.5%) to 71.0% (95% CI, 43.1-88.8%) for children and 7.2% (95% CI, 2.7-17.6%) to 83.3% (95% CI, 64.1-93.3%) for adults. Children with abdominal pain and a diagnosis of appendicitis evaluated in a pediatric ED were at decreased odds (pain odds ratio, 0.6 [95% CI, 0.3-0.9]; appendicitis odds ratio, 0.2 [95% CI, 0.0-0.7]) of receiving CT than were those evaluated in general EDs. CT use has decreased in the evaluation of abdominal pain in children, perhaps because of research findings and efforts to implement an ultrasound-first strategy for suspected appendicitis. In contrast, CT use has continued to increase among adults with abdominal pain in EDs.