Diagnostic imaging and negative appendectomy rates in children: effects of age and gender.

BACKGROUND AND OBJECTIVES Diagnostic imaging is often used in the evaluation of children with possible appendicitis. The utility of imaging may vary according to a patient's age and gender. The objectives of this study were (1) to examine the use of computed tomography (CT) and ultrasound for age and gender subgroups of children undergoing an appendectomy; and (2) to study the association between imaging and negative appendectomy rates (NARs) among these subgroups. METHODS Retrospective review of children presenting to 40 US pediatric emergency departments from 2005 to 2009 (Pediatric Health Information Systems database). Children undergoing an appendectomy were stratified by age and gender for measuring the association between ultrasound and CT use and the outcome of negative appendectomy. RESULTS A total of 8 959 155 visits at 40 pediatric emergency departments were investigated; 55 227 children had appendicitis. The NAR was 3.6%. NARs were highest for children younger than 5 years (boys 16.8%, girls 14.6%) and girls older than 10 years (4.8%). At the institutional level, increased rates of diagnostic imaging (ultrasound and/or CT) were associated with lower NARs for all age and gender subgroups other than children younger than 5 years, The NAR was 1.2% for boys older than 5 years without any diagnostic imaging. CONCLUSIONS The impact of diagnostic imaging on negative appendectomy rate varies by age and gender. Diagnostic imaging for boys older than 5 years with suspected appendicitis has no meaningful impact on NAR. Diagnostic strategies for possible appendicitis should incorporate the risk of negative appendectomy by age and gender.