Diagnostic value of unenhanced helical CT in adult patients with suspected acute appendicitis

Abstract

Clinical diagnosis of appendicitis is usually made on the basis of history, physical examination and laboratory studies. Approximately 30-45% of patients with suspected appendicitis present with atypical clinical and laboratory findings. Recently graded compression ultrasound and thin section unenhanced helical CT have been used to establish diagnosis for patients with suspected acute appendicitis. The purpose of this study was to determine the diagnostic accuracy of thin section unenhanced helical CT protocol in adult patients with suspected acute appendicitis. CT scans obtained when patients presented with right lower quadrant pain and the clinical impression was equivocal for appendicitis were evaluated. Of 296 patients referred for CT, 123 patients subsequently underwent surgery. Appendicitis had been correctly predicted in 104 of 108 patients surgically proven to have appendicitis. Unenhanced helical CT in the diagnosis of acute appendicitis had a sensitivity of 96%, specificity of 98%, positive predictive value of 97% and negative predictive value of 98%. If no definite inflammatory changes are detected, on the basis of our experience we recommend that the patient be monitored clinically, and that thin section unenhanced helical CT is the optimal technique to detect acute appendicitis in adult patients.

Acute appendicitis: diagnostic value of nonenhanced CT with selective use of contrast in routine clinical settings

“…Specific primary and secondary signs have been described for CT diagnosis of acute appendicitis. Primary signs require visualization of the appendix, an important diagnostic goal that is strongly dependent by appendiceal size, amount of periappendiceal fat, and degree of ileocecal bowel opacification [11]. Primary signs are related to the morphological aspect of the appendix and include appendiceal enlargement, wall thickening, ill-defined margins, Fig.…”

“…Initial NECT scans were prospectively interpreted as negative if the appendix had intraluminal gas extending to its tip or if a nonopacified appendix was less than 6 mm in diameter. Because up to 42% of asymptomatic patients have an appendix diameter more than 6 mm [9], in symptomatic patients, CT was interpreted as positive if the appendix was greater than 6 mm in diameter and there were periappendiceal inflammatory changes, or if the appendix was not identified but secondary signs were present, with the center of inflammation in the expected region of the appendix [10,11]. An isolated appendicolith was not considered sufficient for the diagnosis of acute appendicitis [12].…”

CT appearance of the normal appendix in adults

“…Dixon and Goldstone reported in 2002 [10], about the Euratom Directive, that the use of CT for suspected acute appendicitis can avoid inappropriate surgery or delayed diagnosis, so the risks of radiation exposure more than outweigh the possible benefits. Although several CT signs of appendicitis are well described in the radiological literature [11], few studies have evaluated the normal appendix on CT [12][13][14][15]; CT criteria for normal size and wall thickness are based on data from the ultrasound literature, and CT criteria for the intraluminal content and location are based in large part on experience with barium studies [16][17][18].…”

The Effect of Computed Tomography on Surgeon’s Decisions in Suspected Appendicitis Cases

“…However, some studies did not find any significant difference with the use of CT [6]. The sensitivity and specificity of CT for diagnosis of appendicitis is quite high, and reported to be 87-100% and 83-100% respectively [3,7,8]. The overall accuracy, positive predictive value and negative predictive value of CT were reported to be 94-98%, 92-98% and 95-100% respectively [8,9].…”