Alvarado Score Calculator — Appendicitis Risk

Formula

How this is calculated

The Alvarado score (also called MANTRELS) was published in 1986 by Alfredo Alvarado as a simple point-based system to assist clinicians in deciding when acute appendicitis is likely enough to warrant surgical intervention. It assigns points to eight clinical features — three symptoms (migration of pain to the right iliac fossa, anorexia, nausea/vomiting), three signs (right iliac fossa tenderness, rebound tenderness, fever > 37.3 °C), and two lab findings (leukocytosis > 10,000/µL, left shift in the white-cell differential). RIF tenderness and leukocytosis are each worth 2 points; the rest are 1 point each, for a maximum of 10.

The traditional cut-offs are: 1–4 points — appendicitis unlikely, consider discharge; 5–6 points — equivocal, observation or imaging (CT/ultrasound) recommended; 7–8 points — probable appendicitis, surgical consultation; 9–10 points — almost certain appendicitis, operative intervention.

The score has a sensitivity of roughly 96–99% for scores ≥ 7 in adult males but is less specific, leading many centres to use it as a triage aid alongside imaging rather than as a standalone decision tool. It performs less well in children and women of childbearing age (where gynaecological causes mimic appendicitis). All clinical decisions must be made by a qualified clinician.