Interval appendectomy as a safe and feasible treatment approach after conservative treatment for appendicitis with abscess: a retrospective, single-center cohort study

Emergency appendectomy (EA) is the gold standard management for acute appendicitis (AA). However, whether EA or interval appendectomy (IA) after conservative treatment is the optimal approach in AA with abscess remains controversial. This study compared IA and EA in patients presenting with AA accompanied by abscess. This was a retrospective single-center study including 446 consecutive patients undergoing appendectomy between April 2009 and March 2023. AA with abscess was defined as a pericecal abscess observed by computed tomography or abdominal ultrasonography, and patients with signs of peritoneal irritation were excluded. Perioperative outcomes were compared between the patients who directly underwent EA and those who underwent IA after conservative treatment. Among 42 patients (9.4%) with AA and abscess, 34 and 8 patients underwent IA and EA, respectively. The rates of ileocecal resection and postoperative complications were lower in the IA group than in the EA group (3% vs. 50%, P < 0.001 and 9% vs. 75%, P < 0.001, respectively). Colonoscopy before IA was performed in 16 of the 17 patients aged ≥ 40 years in the IA group, and one patient underwent ileocecal resection because of suspicious neoplasm in the root of the appendix. IA after conservative treatment might be considered as the useful therapeutic option for AA with abscess. Colonoscopy during the waiting period between the initial diagnosis and IA should be considered in patients aged ≥ 40 years who may have malignant changes. Implementing IA as a first-line treatment will be beneficial to both patients and healthcare providers.