Admission Blood Biomarkers for Differentiating Acute Appendicitis from Acute Enteritis in Children Younger than Five Years: A Retrospective Cohort Study

Background/Objectives: Acute abdominal pain in children younger than five years is a diagnostic challenge because acute appendicitis and acute enteritis share overlapping clinical features, and delayed recognition of appendicitis increases the risk of perforation and postoperative complications. We aimed to identify admission blood biomarkers that reliably distinguish these two conditions and to quantify their diagnostic accuracy.

Methods

We conducted a retrospective observational cohort study at the Children’s Hospital Zagreb covering the period from 1 January 2016 to 1 January 2026. Children younger than five years with a confirmed diagnosis of acute appendicitis (Group A, n = 80) or acute enteritis (Group B, n = 66) were included. Appendicitis was confirmed intraoperatively and histopathologically, whereas enteritis was confirmed by stool testing, imaging, and clinical course. The complete blood count with differential, derived inflammatory indices, and C-reactive protein obtained on admission were compared using the Mann–Whitney U test, receiver operating characteristic analysis, and multivariable logistic regression.