Background : Appendectomy can be challenging and occasionally converted to extensive resection for complicated appendicitis. However, optimal treatment strategies can be developed using preoperative risk assessment. Thus, we aimed to investigate the preoperative predictors of extensive resection in complicated appendicitis patients undergoing surgery. Materials and methods : In total, 173 complicated appendicitis patients undergoing surgery between 2014 and 2019 were classified into the appendectomy (n = 153) or extensive resection (n = 20) groups. Clinicopathological factors and surgical outcomes were compared between groups. Results : Extensive resection was performed in 20 of 173 complicated appendicitis patients (11.5%). The rates of having defects in the wall structure at the appendix root on computed tomography images were significantly higher, and the duration from onset to surgery was significantly longer in the extensive resection group. Significant differences were found in operative duration, blood loss and postoperative hospitalization, but none in the incidence of postoperative complications between groups. Multivariate analyses showed that defects in the wall structure at the appendix root and five days or longer from onset were identified as independent predictors of extensive resection. Conclusions : Defects in the wall structure at the appendix root and five days or longer from onset predict extensive resection performance in complicated appendicitis patients
