PurposeThe treatment strategies for acute appendicitis differ depending on the facility, and various studies have investigated the usefulness of conservative treatment with antibiotics, laparoscopic surgery, and interval appendectomy (IA). However, although laparoscopic surgery is widely used, the clinical strategy for acute appendicitis, especially complicated cases, remains controversial. We assessed a laparoscopic surgery-based treatment strategy for all patients diagnosed with appendicitis, including those with complicated appendicitis (CA).MethodsWe retrospectively analysed patients with acute appendicitis treated in our institution between January 2013 and December 2021. Patients were classified into uncomplicated appendicitis (UA) and CA groups based on computed tomography (CT) findings on the first visit, and the treatment course was subsequently compared.ResultsOf 305 participants, 218 were diagnosed with UA and 87 with CA, with surgery performed in 159 cases. Laparoscopic surgery was attempted in 153 cases and had a completion rate of 94.8% (145/153). All open laparotomy transition cases (n= 8) were emergency CA surgery cases. No significant differences were found in the incidence of postoperative complications in successful emergency laparoscopic surgeries. In univariate and multivariate analyses for the conversion to open laparotomy in CA, only the number of days from onset to surgery ≥ 6 days was an independent risk factor (odds ratio: 11.80;P< 0.01).ConclusionLaparoscopic surgery is preferred in all appendicitis cases, including CA. Since laparoscopic surgery is difficult for CA when several days from the onset have passed, it is necessary that surgeons make an early decision on whether to operate.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12893-023-02070-y.