Revisiting the Appendiceal Diameter via Ultrasound for the Diagnosis of Acute Appendicitis

Objectives This study aims to investigate the optimal outer appendiceal diameter via ultrasound for the diagnosis of acute appendicitis. Methods A retrospective chart review was conducted on patients (ages, 2-18 years) presenting to an urban pediatric emergency department between January 1, 2009 and December 31, 2010 with suspected acute appendicitis. Children were considered as having suspected acute appendicitis if they (1) presented with acute abdominal pain and had either a surgical consult or an abdominal ultrasound, or (2) presented or transferred with the stated suspicion of acute appendicitis. Pathology reports were used to confirm the diagnosis of appendicitis. The appendiceal diameters were determined by board-certified pediatric radiologists. Results A total of 320 patient charts were reviewed (females, 57%; mean age, 10.9; SD, 3.9). Seventy-two percent (N = 230) of the patients screened positive for acute appendicitis via ultrasound, 69% (N = 222) had confirmed acute appendicitis, 75% (N = 239) of the ultrasound reports included an outer appendiceal diameter. Overall, ultrasound was found to be highly sensitive (91%) and moderately specific (74%). With an outer appendiceal diameter of 6 mm as a cutoff, ultrasound had an excellent sensitivity (100%) but poor specificity (43%). With an outer diameter of 7 mm as a cutoff, sensitivity decreased to 94% but specificity increased to 71%. With increasing cutoff size, the sensitivity decreased and specificity increased. Conclusions Our data suggest that the optimal outer appendiceal diameter for the diagnosis of acute appendicitis should be 7 mm instead of the currently used 6 mm.