Added value of ultrasound re-evaluation for patients with equivocal CT findings of acute appendicitis: A preliminary study

Abstract

Purpose: To prospectively estimate the additional diagnostic value of ultrasound (US) re-evaluation for patients with equivocal computed tomography (CT) findings of acute appendicitis. Methods: Between April 2011 and October 2011, 869 consecutive patients with suspected appendicitis who were referred for CT were included. The likelihood of appendicitis was prospectively categorized into five categories. US re-evaluation was recommended for patients in the 'equivocal appendix' and 'probably not appendicitis' groups. The overall negative appendectomy rate during the study period was compared with the rate of the previous year, and negative appendectomy rates of the US and non-US evaluation groups were also compared. Results: Among 869 patients, 71 (8.2 %) had equivocal appendicitis findings and 63 (7.2 %) were diagnosed as probably not appendicitis. The sensitivity and specificity of CT combined with US re-evaluation group (100 % and 98.1 %, respectively) exceeded those of the CT alone group (93 % and 99 %; equivocal group considered as negative appendicitis, 100 % and 89.9 %; as positive, respectively, P < 0.0001). After adding US re-evaluation, the overall negative appendectomy rate in our institution decreased from 3.4 to 2.3 %. Conclusion: For patients with equivocal CT findings of acute appendicitis, US re-evaluation can improve diagnostic accuracy and decrease the rate of negative appendectomies. © 2013 European Society of Radiology.