ThP6.14 - The Diagnostic Utility of C-Reactive Protein in Acute Appendicitis

Abstract Aim This study sought to determine the value of C-Reactive Protein (CRP) as a diagnostic marker in acute appendicitis. Methods All patients > 18 years presenting to the surgical assessment unit with acute appendicitis in 2022 were retrospectively identified. Data including patient demographics, admission CRP, CT results and operative findings were analysed. Results This study identified 130 patients with a median age of 35 years. Operative management was undertaken in 85% of patients (n=110) and conservative in 15% (n=20). Of these, four required conversion to operative management. No significant difference in CRP was identified between conservative and operative management. CT was performed in 84% of patients. Of these, 98% (n=107) were suggestive of acute appendicitis - 85% uncomplicated (n=91) and 15% (n=16) complicated. CRP was significantly higher in patients with CT- diagnosed complicated appendicitis (p<0.001). Operative assessment demonstrated 76 patients (58%) with uncomplicated and 38 (29%) with complicated appendicitis, with CRP significantly elevated in complicated appendicitis (median 119.5 vs 21, p<0.001). A CRP cut-off of 96mg/L showed reasonable predictive value of complicated appendicitis (sensitivity=61%, specificity=88%) with AUC value of 0.76 (95%CI: 0.66-0.87). CRP also showed value as a predictor of perforation and abscess (AUC=0.79 (95%CI: 0.67-0.90) and 0.76 (95%CI: 0.63-0.89) respectively. Optimal CRP cut off for perforation was 84mg/L (sensitivity=73%, specificity=88%) and 96mg/L (sensitivity=73%, specificity=81%) for abscess. CRP was not significantly elevated in necrotic or gangrenous appendicitis. Conclusions CRP levels correlate with appendicitis severity in both CT and operative assessment and may be a useful predictor of perforation and abscess formation.