Does the presence of an appendicolith or abscess predict failure of nonoperative management of patients with acute appendicitis?

Purpose Nonoperative management (NOM) has been widely accepted as one of the standard treatments for patients with acute appendicitis. However, predictive factors for the failure of NOM have not been thoroughly investigated. Methods A total of 196 patients with acute appendicitis underwent NOM between April 2014 and December 2020. Of these 196 patients, 24 patients failed NOM and required emergency surgery (failure group: n = 24), while the other 172 patients were successfully treated with NOM (success group: n = 172). These two groups were compared, and the predictive factors for the failure of NOM were investigated. Results The number of patients who had a previous history of stroke was significantly increased in the failure group (12.5% vs. 2.9%, p = 0.026). Incarceration of an appendicolith on CT images was significantly associated with the failure group (20.8% vs. 1.7%, p < 0.001), while neither the presence of an appendicolith nor abscess was associated. The presence of periappendiceal fluid was significantly associated with the failure group (50.0% vs. 26.7%, p = 0.019). The incarceration of an appendicolith ( p < 0.001, odds ratio = 19.85) and periappendiceal fluid ( p = 0.009, odds ratio = 3.62) were found to be independent risk factors for failure of NOM. Neither the presence of an appendicolith nor abscess was associated with the recurrence of appendicitis. Conclusions The presence of an appendicolith or abscess was not a crucial factor for surgery. Incarceration of an appendicolith and periappendiceal fluid on CT images was predictive factors for the failure of NOM.