Pediatric Appendicitis Risk Calculator

Last revised by Dr Jeremy Jones on 18 Sep 2021

The Pediatric Appendicitis Risk Calculator (pARC) is a clinical decision rule and predictor of the likelihood of acute appendicitis in pediatric patients.  Due to the non-categorical data of some variables within the criteria, an integrated calculator is required to use this tool.

  • age
  • sex
    • male
      • 5-7.9 years
      • 8-13.9 years
      • 14-18 years
    • female        
      • 5-7.9 years
      • 8-11.9 years
      • 12-18 years
  • duration of pain
    • <24 hours
    • 24-47 hours
    • 48-96 hours
  • pain with walking or hopping
  • maximal tenderness in RLQ
  • migration of pain to RLQ
  • guarding
  • absolute neutrophil count
  • community ED or pediatric ED setting
  • very low: <5%
  • low: 5-14%
  • intermediate: 15-84%
  • high: 85%

For a risk category of low/very low, the NPV is >98% 2

For a risk category of high, the PPV is 85% 2

  • abdominal trauma in the past 7 days
  • current pregnancy
  • history of abdominal surgery including appendectomy

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