09.04 Patient and provider factors associated with ultrasound visualization in pediatric appendicitis

B. L. Vey¹, H. E. Arnold¹, R. P. Cutts¹, A. U. Patel¹, C. Travers³, J. Loewen², K. Braithwaite², K. E. Applegate², K. Heiss¹, M. V. Raval^{1  1}Emory University School Of Medicine,Division Of Pediatric Surgery, Department Of Surgery,Atlanta, GA, USA ²Emory University School Of Medicine,Division Of Pediatric Radiology, Department Of Radiology And Imaging Sciences,Atlanta, GA, USA ³Emory University School Of Medicine,Department Of Pediatrics,Atlanta, GA, USA

Introduction:
When indicated, ultrasound (US) is the preferred diagnostic imaging modality for children with possible appendicitis. Unfortunately, in over half of studies US fails to visualize the appendix. Factors such as study duration, time of day, gender, obesity, and technologist experience have all been implicated as influencing US visualization rates. The purpose of this study was to identify which factors are associated with emergency room US visualization rates in a pediatric center with 24-hour US availability.

Methods:
Single-center retrospective review of all US studies obtained from January 1 to March 31, 2016 for children ages 5-18yo in the emergency room. Each US was assessed for duration, technologist experience, time of day, and patient factors including age, sex, and obesity.  Technologists were considered ‘low experience’ with less than one year of experience in a dedicated pediatric setting. Regression models were used to examine association of patient and study factors with visualization.

Results:
649 US studies were identified as direct assessments of the appendix for cases of potential appendicitis. Overall, the appendix was fully visualized in 271 (41.8%) of studies. Compared to older patients, younger children (ages 5-9) were more likely to have the appendix visualized (Odds Ratio (OR) 3.09, 95% Confidence Interval (CI) 1.97-4.85). Males were more likely to have visualization compared to females (OR 1.96, 95%CI 1.42-2.71). Patient obesity, defined as greater than 95^th percentile weight for age, did not significantly impact visualization rates (42.1% vs 41.7%, p=0.93). There were 28 US technologists and 194 studies (30%) were performed by technologists with low experience. Technologists’ experience did not significantly impact visualization rate (OR 1.09, 95%CI 0.76-1.56). Visualization rates were higher during the weekday nighttime hours of 10pm to 8am and weekends compared to daytime hours (46.1% versus 37.1%, P=0.02). There was slight decrease in the visualization rate in the early evening hours (Figure).

Conclusion:
Overall, complete appendix visualization on US in a pediatric emergency setting remains low. Visualization is highest in males and younger patients and is not compromised by obesity.  Efforts are needed to understand how best to improve US performance overall and in older children and females. Visualization does not appear to be associated with technologists’ experience and is not compromised on nights and weekends. Pediatric centers with available highly trained technologists may provide after-hours US coverage for appendicitis evaluation without sacrificing quality.