Periappendiceal fluid collection on preoperative computed tomography can be an indication for interval appendectomy: a retrospective study

Background The treatment strategies for acute appendicitis, such as emergency appendectomy (EA), interval appendectomy (IA), and repeating nonoperative management (NOM), are controversial. In this study, we examined the preoperative factors that can be used to distinguish which patients should undergo IA. Methods We retrospectively identified 902 patients who underwent surgery for appendicitis in our hospital from January 2010 to December 2021. Of these patients, 776 were included in this study. The patients were divided into two groups: those with a periappendiceal fluid collection (PAFC) on preoperative computed tomography (PAFC-positive group, n = 170) and those without a PAFC (PAFC-negative group, n = 606). In each group, we compared patients who underwent EA and IA. Results In the PAFC-positive group, patients who underwent EA had a significantly higher postoperative complication rate than those who underwent IA (40.5% vs. 24.0%, p = 0.037). In the multivariate analysis, only the presence of PAFC was significantly associated with an increased risk of postoperative complications (odds ratio, 7.11; 95% confidence interval, 2.73–18.60; p < 0.001). The presence of PAFC alone was not significantly associated with an increased risk of IA or NOM failure (odds ratio, 1.48; 95% confidence interval, 0.19–11.7; p = 0.71). The rate of neoplasia on pathologic examination was significantly higher in the PAFC-positive than PAFC-negative group (7.6% vs. 1.5%, p < 0.001); the rate of carcinoma was also higher in the PAFC-positive group (2.4% vs. 0.17%, p = 0.02). Conclusions The presence of PAFC on preoperative computed tomography was found to be a risk factor for postoperative complications but not IA or NOM failure. It was also correlated with neoplasia as the etiology of appendicitis. Therefore, PAFC positivity is useful as an indication for IA.