Which Factors Influence the Detection of an Inflamed Appendix: Comparative Assessment of Ultrasonography and CT

ABSTRACT

PURPOSE: To compare and assess factors influencing the detection of an inflamed appendix by both ultrasonography (US) and CT. MATERIALS AND METHODS: We retrospectively analyzed US and CT findings of 58 patients with confirmed acute appendicitis (42 patients with perforation and 16 patients without perforation), in which both preoperative US and CT scans were performed. We compared the use of US and CT for the diagnostic accuracy of acute appendicitis, and determined the detection rate for an inflamed appendix. According to the location of the appendix, the amount of mesenteric fat content in lower abdominal cavity, the presence of cecal wall thickening, and the presence of pericecal fluid or an abscess, the use of US and CT were compared for the determination of the detection rate of an inflamed appendix. RESULTS: The diagnostic accuracies for US and CT for acute appendicitis in our study group were both 93.1%, and there was no difference between the use of the two modalities. Although the detection rate of an inflamed appendix was slightly higher for US (93.1%) than for CT (84.5%), the difference between the use of the two modalities was not significant (p > 0.05). There was no significant difference in the detection rate of an inflamed appendix between the use of US and CT according to location of appendix, the amount of mesenteric fat content and the presence of cecal wall thickening. A pelvic location of the inflamed appendix and the presence of pericecal fluid or an abscess, were factors that significantly increased the detection rate for US than for CT (p < 0.05). CONCLUSION: The use of US for diagnosis of acute appendicitis is as useful as the use of CT. US is especially useful to detect an inflamed appendix more effectively than CT in cases where the appendix is in a pelvic location and presents with pericecal fluid or an abscess.