IMAGE FINDINGS AND THE ADDED VALUE OF CT SCAN IN THE DIAGNOSIS OF ACUTE APPENDICITIS

Abstract

Background: Appendicitis is one of the most common causes of acute abdominal pain, requiring surgical treatment. The problem of how to make an early and accurate diagnosis of acute appendicitis should be prioritized. Aims: To describe the image findings and evaluate the added value of CT scan in the diagnosis of acute appendicitis. Materials and Method: 121 patients were admitted to Hue University Hospital with suspicion of having acute appendicitis from April 2016 to July 2017. There would be a complementary CT scan if the ultrasonography result was inconclusive or irrelevant to clinical manifestations. The results of ultrasonography and CT scan were then correlated with surgical findings and treatment. Results: 39.7% of 121 patients with suspicion of acute appendicitis needed a complementary CT scan after ultrasonography had been performed. CT scan also detected 19 alternative diagnoses that caused acute abdominal pain. The direct signs of acute appendicitis on CT scan with high sensitivity were enlarged appendix with over 6mm in diameter (93.8%), appendiceal wall thickening (87.5%), appendiceal wall enhancement (90.6%); the signs with high specificity were maximum depth of intraluminal appendiceal fluid greater than 2,6mm (100%), appendiceal wall enhancement (87.5%) and appendicolith (87.5%). Among indirect signs of acute appendicitis on CT scan, the sign with the highest sensitivity and specificity was periappendiceal fat stranding (90.6% and 100% respectively). The sensitivity, specificity and accuracy of CT scan in diagnosis of acute appendicitis were 90.6%, 100% and 93.8% in that order. The sensitivity, specificity and accuracy of the diagnosis pathway using primary ultrasonography and complementary CT scan was 97.1%, 94.1% and 96.7%. Conclusion: The signs of acute appendicitis on CT scan with high sensitivity were enlarged appendix with over 6mm in diameter, periappendiceal fat stranding, appendiceal wall thickening and enhancement. The signs of acute appendicitis on CT scan with high specificity were periappendiceal fat stranding, maximum depth of intraluminal appendiceal fluid greater than 2.6mm, appendiceal wall enhancement and appendicolith. The diagnosis pathway using primary ultrasonography and complementary CT scan yielded a high diagnostic sensitivity, specificity and accuracy for acute appendicitis. Key words: Acute appendicitis, complementary CT scan