Purpose: Surgery and nonoperative management (NOM) are the treatment modalities for acute appendicitis (AA). There is little evidence to indicate which treatment method should be performed according to the patient's condition or disease severity, surgical extension, and timing after an appendectomy. This study aimed to evaluate postoperative intra-abdominal abscess (PIAA) associated with these factors.Methods: The medical records of 839 patients who underwent appendectomy after a diagnosis of AA between 2019 and 2020 at Gangneung Asan Medical Centre were reviewed retrospectively. The factors associated with PIAA were evaluated.Results: Postoperative complications occurred in 92 patients. Following appendectomy, 16 (1.9%), 83 (9.9%), and three (0.4%) patients developed PIAA, surgical site infection, and incisional hernia, respectively. The American Society of Anesthesiologists class, complicated appendicitis on preoperative abdominal computed tomography, failure of NOM, and extensive surgery above appendectomy were associated with the development of PIAA. However, a laparoscopic approach, irrigation, indwelling drain, ultrasonic dissection, and use of sterile bags were not associated with the development of PIAA.Conclusion: NOM for some patients with complicated AA is an attractive treatment modality. However, to reduce the incidence of PIAA, the application of NOM should be circumspect considering patient factors and the nature of acute appendicitis. Furthermore, appendectomy should be performed as early as possible for patients not indicated for NOM.