Differentiating Uncomplicated From Complicated Acute Appendicitis in Paediatric Patients With C-Reactive Protein and Imaging Findings-A Retrospective Single Centre Study in 1149 Patients.

AIM: Acute appendicitis is one of the most common surgical emergencies in children and differentiating uncomplicated appendicitis from complicated is crucial. Our aim was to examine accuracy of preoperative C-reactive protein (CRP) combined with imaging findings in identifying patients with uncomplicated outcome. METHODS: We retrospectively examined 1520 patients treated for acute appendicitis at the Helsinki University Children's Hospital during 2013-2023. Receiver operating characteristics (ROC) curves and areas under the ROC curves (AUROC) were used to estimate optimal CRP cutoff values with maximum sum of sensitivity and specificity for predicting uncomplicated outcomes in patients with uncomplicated imaging findings. RESULTS: Among the 1149 included patients, preoperative imaging included ultrasound examination (98.6%), MRI (9.8%), and/or CT (2.1%). In total, 314 (27.3%) patients had a complicated outcome with higher preoperative CRP levels (133 ± 83 mg/L) compared to patients with uncomplicated outcomes (47.2 ± 46.3 mg/L, p < 0.001). In patients with uncomplicated imaging findings, the optimal CRP cutoff was 58 mg/L with AUROC 0.819 (95% CI 0.78-0.86), 85.7% sensitivity, and 90.0% specificity. Using CRP cutoff ≤ 58 mg/L, only 20 of 450 patients with uncomplicated imaging findings had a complicated outcome. CONCLUSION: With CRP cutoff ≤ 58 mg/L and uncomplicated imaging findings, only a minority (4.4%) of children with acute appendicitis had a complicated outcome.