Alvarado Score
Eight factors, remembered as MANTRELS. Right lower quadrant tenderness and leukocytosis carry 2 points each; the rest carry 1.
0 / 10 — Low probability
Low probability. Appendicitis is unlikely but not excluded — a short period of observation with repeat examination discriminates better than a single score.
Notes
The 1–4 / 5–6 / 7–10 grouping is convention, not part of Alvarado's paper, which reported diagnostic weights rather than management bands. The score raises or lowers your suspicion; it does not decide the operation.
It performs worse in women and in children. Systematic review found it reasonably sensitive for ruling out appendicitis at low scores but poorly specific at high ones, and least reliable in women of reproductive age, where gynaecological mimics are common. A high score there is a reason to image, not to skip imaging.
Two of the eight need bloods — leukocytosis and the left shift, which together carry 3 of the 10 points. The score cannot be completed at triage on history and examination alone.
It was derived retrospectively in 1986, before routine CT and ultrasound. Where imaging is available it supplements the score rather than the other way round.