“…However, US has some limitation: important layer of fat tissue in obese children, digestive distension due to air accumulation and last, but not least, experience of the operator [5] . Overall, sensitivity, specificity, PPV and NPV of US for diagnosis of acute appendicitis in pediatric population have been reported as ranging from 58% to 97.1% [6][7][8][9] , 41.7 to 97.7% [6][7][8][9] , 77 to 95% [6,7] and 39 to 61.5% [6][7][8] , respectively. However, authors reported that these results were different when comparing uncomplicated and complicated appendicitis, with lower sensitivity in the latter case [10,11] .…”