Right hydronephrosis as a sign of complicated appendicitis

Objective: Acute appendicitis is known for one of the most common cause of acute abdomen. However, it is still challenging to clearly distinguish complicated from uncomplicated appendicitis preoperatively. We investigated the association between right hydronephrosis and complicated appendicitis compared with other computed tomography (CT) findings of acute appendicitis. Materials and methods: 1275 patients who pathologically diagnosed with acute appendicitis were included. They were classified into the complicated appendicitis and uncomplicated appendicitis groups based on their histopathological results. We reviewed their CT findings, including right hydronephrosis, appendiceal wall defect, periappendiceal abscess, extraluminal or intraluminal free air, appendicolith, appendiceal dilatation, appendiceal wall thickening, periappendiceal infiltration, periappendiceal fluid collection, and ascites. Comparison between the two groups was performed and the diagnostic performance of each CT finding was evaluated. The location of appendix and periureteral extension of periappendiceal infiltration were evaluated in patients with right hydronephrosis. Results: Out of 1275 patients, 29 (2.3 %) patients showed right hydronephrosis. Right hydronephrosis was significantly related to complicated appendicitis with the odds ratio of 4.90 (95 % confidence interval, 1.62−14.83; P = 0.005). Right hydronephrosis yielded specificity of 99.3 %. All patients with right hydronephrosis accompanied with periappendiceal infiltration and 28 (96.6 %) patients showed periureteral extension. Subcecal and pelvic areas are the most common locations, with 11 (37.9 %) patients each. Conclusion: The presence of right hydronephrosis was specific finding for complicated appendicitis and it could be considered as one of indirect sign of complicated appendicitis.