Retained appendicolith in an inflamed appendix.

Risk factors for progression to advanced appendicitis have not been clarified. The purpose of this study was to investigate whether the presence of appendicolith on computed tomography (CT) is related to progression of pathologic grade. We performed a retrospective review of 46 consecutive patients who underwent appendectomy and who had an inflamed appendix on CT scan. Patients were divided into two groups: group A underwent CT scan within 10 h of onset of symptoms, and group B was scanned after more than 10 h of symptoms. The presence or absence of appendicolith on CT as well as pathologic inflammatory grade was recorded. We analyzed correlation between the presence of appendicolith and ultimate pathologic grade in each group. Appendicoliths were detected on CT in 17 (17/36) of group B. The presence of appendicolith on CT in group B was significantly correlated with pathologic severity (p = 0.006). Retained appendicolith that is identified in an inflamed appendix on CT more than 10 h after onset of symptoms may be useful as a predictor of pathologic inflammatory grade of appendicitis.