Acute Appendicitis: Investigating an Optimal Outer Appendiceal Diameter Cut-Point in a Pediatric Population

BackgroundAcute appendicitis is the most common cause of abdominal pain in children requiring operative intervention. Among a number of sonographic criteria to aid in the diagnosis of appendicitis, an outer diameter >6 mm is the most objective and widely accepted. However, there is a lack of evidence-based standards governing this consensus.Study ObjectivesThe aim of this study was to determine the outer appendiceal diameter that maximizes sensitivity and specificity in a pediatric population.MethodsA retrospective review of all urgent diagnostic ultrasounds (US) was performed over 2 years in children aged <18 years. The diagnostic accuracy of various cut-points was assessed by calculating the sensitivity and specificity and plotting a receiver operating characteristic (ROC) curve.ResultsThe study sample consisted of 398 patients in whom the appendix was visualized on US. The median outer appendiceal diameter was significantly higher in the surgical group compared to the nonsurgical group (9.4 mm; range = 8.1–12.0 vs. 5.5 mm; range = 4.4–6.5, p < 0.01). The optimal cut-point with the greatest area under the ROC curve was determined to be an outer appendiceal diameter of 7.0 mm.ConclusionsIn our patients, adopting a 7-mm rather than a 6-mm appendiceal diameter threshold would balance a greater number of missed cases of acute appendicitis for a reduction in the number of unnecessary surgeries.