pARC Score — Pediatric Appendicitis Risk Calculator

The Pediatric Appendicitis Risk Calculator (pARC) is a validated clinical prediction tool that estimates the probability of appendicitis in children without requiring laboratory tests or imaging in its base form. Inputs include eight clinical and basic laboratory variables. The pARC was derived from over 2,000 children (ages 5–18 years) in the PECARN network and provides a continuous probability estimate (0–100%) rather than a categorical score. It is among the most accurate non-ultrasound pediatric appendicitis predictors.