Accuracy of computed tomography in staging acute appendicitis and its impact on surgical outcome and strategy: a multi-center retrospective case-control study

Introduction: The aims of this study were to evaluate the concordance between AAST-CT appendicitis grading criteria, first published in 2014, and surgical findings and to assess the impact of CT staging on the choice of surgical approach.

Methods: This was a multi-center retrospective case-control study including 232 consecutive patients undergoing surgery for acute appendicitis and who had undergone preoperative CT evaluation between 1 January 2017 and 1 January 2022. Appendicitis severity was classified in 5 grades. For each degree of severity, the surgical outcome between patients undergoing open and surgical approach was compared.

Results: An almost perfect agreement (k = 0.96) was found between CT and surgery in staging acute appendicitis. The vast majority of patients with grade 1 and 2 appendicitis underwent laparoscopic surgical approach and showed low morbidity rate. In patients with grade 3 and 4 appendicitis, laparoscopic approach was adopted in 70% of cases and was associated, if compared to open, with a higher prevalence of postoperative abdominal collections (p = 0.05; fisher's exact test) and a significantly lower prevalence of surgical site infections (p = 0.0007; fisher's exact test). All the patients with grade 5 appendicitis were treated by laparotomy.

Conclusions: AAST-CT appendicitis grading system seems to show a relevant prognostic value and a potential impact on the choice of surgical strategy, directing toward a laparoscopic approach in patients with grade 1 and 2, an initial laparoscopic approach, replaceable by the open one, for grade 3 and 4 and an open approach in patients with grade 5.