Effectiveness of a staged US and CT protocol for the diagnosis of pediatric appendicitis: reducing radiation exposure in the age of ALARA.

Purpose: To evaluate the effectiveness of a staged ultrasonography (US) and computed tomography (CT) imaging protocol for the accurate diagnosis of suspected appendicitis in children and the opportunity for reducing the number of CT examinations and associated radiation exposure.
Materials and Methods: This retrospective study was compliant with HIPAA, and a waiver of informed consent was approved by the institutional review board. This study is a review of all imaging studies obtained in children suspected of having appendicitis between 2003 and 2008 at a suburban pediatric emergency department. A multidisciplinary staged US and CT imaging protocol for the diagnosis of appendicitis was implemented in 2003. In the staged protocol, US was performed first in patients suspected of having appendicitis; follow-up CT was recommended when US findings were equivocal. Of 1228 pediatric patients who presented to the emergency department for suspected appendicitis, 631 (287 boys, 344 girls; age range, 2 months to 18 years; median age, 10 years) were compliant with the imaging pathway. The sensitivity, specificity, negative appendectomy rate (number of appendectomies with normal pathologic findings divided by the number of surgeries performed for suspected appendicitis), missed appendicitis rate, and number of CT examinations avoided by using the staged protocol were analyzed.
Results: The sensitivity and specificity of the staged protocol were 98.6% and 90.6%, respectively. The negative appendectomy rate was 8.1% (19 of 235 patients), and the missed appendicitis rate was less than 0.5% (one of 631 patients). CT was avoided in 333 of the 631 patients (53%) in whom the protocol was followed and in whom the US findings were definitive.
Conclusion: A staged US and CT imaging protocol in which US is performed first in children suspected of having acute appendicitis is highly accurate and offers the opportunity to substantially reduce radiation.
(© RSNA, 2011.)