Appendicitis in children -: Impact of US and CT on the negative appendectomy rate

Background/Purpose: Ultrasonography (US) and computed tomography (CT) have proved useful for the evaluation of suspected appendicitis and were introduced as diagnostic tools at our institution about ten and five years ago, respectively. The aim of this study was to evaluate how the negative appendectomy and perforation rates have changed with increased use of US and CT. Methods: The medical records of 600 children who underwent appendectomy during years 1991,1994,1997, and 2000 were reviewed. Perforation in perforated appendicitis was considered to have occurred after admission if the time interval between the first health professional contact and surgery exceeded 12 hours. Results: The total number of appendectomies during the years 1991, 1994, 1997, and 2000 was 406, 334, 407, and 397, respectively. The negative appendectomy rate for the same years was 23%, 8.7%, 8.0%, and 4.0%, respectively. The overall rate of perforations and the perforation rate after admission was 32% and 12%, 34% and 7.3%,3 4% and 13%, and 29% and 2.1%, respectively. The rate of patients who underwent US and CT during each period was 1.0% and 0.0%, 41% and 0.0%, 91% and 21% and 98% and 59%, respectively. Conclusions: The negative appendectomy rate has been substantially reduced after the introduction of both US and CT. The rate of perforation after admission has not increased.