Computed tomography and clinical outcomes in the diagnosis of acute appendicitis: Significance of periappendiceal fat tissue.

Background: This study aimed to elucidate the diagnostic significance of changes in periappendiceal fat density observed on computed tomography (CT) in patients with acute appendicitis (AA).

Methods: Patients who underwent surgery with a diagnosis of AA based on CT findings from January 1, 2020 to December 31, 2020 were included in the study. Patients were divided into three grades. In Grade 1, the periappendiceal tissue appears hypoechoic, indicative of normal tissue. In Grade 2, the periappendiceal tissue is slightly hyperechoic but confined to the periappendiceal area. In Grade 3, dense hyperechoic areas are present not only in the periappendiceal tissue but also extend into surrounding organs and deeper tissues. The groups were compared in terms of clinical, laboratory, and pathological outcomes.

Results: A total of 195 patients-131 males and 64 females-were included in the study. A correlation was identified between grade and several factors: appendix diameter, appendix wall thickness, incidence of lymphadenopathy, and duration of symptoms onset (p<0.001). Conditions such as appendicolitis, free air, and intra-abdominal abscesses were more frequently observed in Grade 3 patients compared to Grade 1 and Grade 2 patients (p=0.002, p<0.001). Both operative time and length of hospital stay were highest in Grade 3 patients (p<0.001). The rate of patients found to have a normal appendix upon pathological examination was significantly higher in Grade 1 than in Grade 2 (p=0.03).

Conclusion: In cases where the diagnosis is uncertain, the hyperechogenicity in periappendiceal tissue observed on CT strengthens the diagnosis of AA. Additionally, cases of AA become increasingly complex as echogenicity in periappendiceal tissue increases.