What it is
The Pediatric Appendicitis Score (PAS), derived by Madan Samuel in 2002, is an eight-item clinical prediction rule built specifically for children with suspected acute appendicitis. It combines history, examination and two laboratory values into a single 0–10 score that triages the child into discharge, observation/imaging, or surgical assessment. It is a stratification aid, not a diagnosis.
The eight items
Each item carries a fixed weight; two items score +2.
| Item | Points |
|---|---|
| RLQ tenderness with cough / percussion / hopping | +2 |
| Tenderness in the right iliac fossa | +2 |
| Anorexia | +1 |
| Fever >38°C | +1 |
| Nausea / vomiting | +1 |
| Leukocytosis (WBC >10,000) | +1 |
| Neutrophilia (PMN >7,500) | +1 |
| Migration of pain to the RLQ | +1 |
Maximum 10. The two heaviest-weighted features are the two tenderness items.
Interpretation bands
The toolkit uses Samuel’s three-band split:
- 0–3 — low risk. Supports discharge with explicit safety-netting.
- 4–6 — intermediate. Observe with serial examination and/or imaging (ultrasound first in children).
- 7–10 — high risk. Supports surgical evaluation.
When to use it
In a child or adolescent with undifferentiated RLQ or periumbilical pain, to rationalise observation versus imaging versus referral. PAS is the more validated paediatric tool and is generally preferred over Alvarado in children. Like all such rules it performs best at identifying the low-risk child; it does not reliably rule appendicitis in.
Worked example
A 10-year-old with pain that migrated to the RLQ (+1), anorexia (+1), one episode of vomiting (+1), RLQ tenderness with hopping (+2), tenderness in the right iliac fossa (+2), temperature 38.4°C (+1), WBC 13,500 (+1), neutrophils 8,200 (+1).
Total = 10/10 → high risk. Supports surgical review; the high score does not replace ultrasound or serial examination.
Pitfalls
- Not a rule-in test. A high score raises probability but does not exclude a normal appendix at operation.
- Both lab thresholds are precise (WBC >10,000, PMN >7,500) — apply them as written rather than eyeballing “the count looks up”.
- A low score does not override a worsening serial examination. Re-score and re-examine.
- Distinct from the Alvarado/MANTRELS score — different items and weights; do not interchange them.
- Validation performance varies by population; the intermediate band is exactly where clinical judgement and imaging matter most.
Run it: Pediatric Appendicitis Score (PAS)
Decision support for qualified clinicians only — verify against current primary guidelines and your clinical judgement.