Interpretation
| Score | Probability | Recommended Action |
|---|
| 0–4 | Low — appendicitis unlikely | Discharge with return precautions; avoid unnecessary CT in children |
| 5–6 | Equivocal — possible appendicitis | Imaging (ultrasound ± CT); active observation; surgical review |
| 7–8 | High — probable appendicitis | Surgical review; proceed to imaging or direct theatre depending on clinical picture |
| 9–10 | Very high — likely appendicitis | Prompt surgical intervention; imaging may not be required if clinical picture is clear |
Clinical Application
The Alvarado Score is the most widely validated clinical scoring tool for acute appendicitis. It can reduce negative appendicectomy rates and guide imaging decisions, particularly in resource-limited settings where CT is not immediately available.
- Score ≤4: Negative predictive value ~95% for appendicitis. Safe to discharge most adult patients with close follow-up instructions.
- Score 5–6: Diagnostic uncertainty zone. Ultrasound first (avoids radiation), then CT if equivocal — standard approach per WSES and SSAT guidelines.
- Score ≥7 in adults: Many surgeons proceed directly to theatre or use CT only to exclude a perforation.
- Children and women of childbearing age: Alvarado may be less specific. Ultrasound is preferred first-line imaging; MRI if ultrasound inconclusive.
- Can be used alongside the AIR Score and Adult Appendicitis Score (AAS) for additional discrimination in intermediate-risk cases.
Evidence & Validation
Derived by Alvarado in 1986 from 305 adult patients. Validated extensively in diverse populations (meta-analysis by Ohle et al. 2011: 42 studies, n=14,397, AUC 0.83–0.90). Sensitivity for scores ≥7 is approximately 82–85%, specificity 81–92%. The score performs equally in developed and resource-limited healthcare settings.
Limitations
- Lower sensitivity in children (score <7 does not reliably exclude appendicitis in paediatric populations)
- Lower specificity in women of childbearing age due to gynaecological causes mimicking appendicitis
- Cannot distinguish simple from gangrenous/perforated appendicitis
- WBC and differential results are needed, making it not entirely "bedside"
- CRP, which improves diagnosis in combination, is not included in the original Alvarado score
References
- Alvarado A. A practical score for the early diagnosis of acute appendicitis. Ann Emerg Med. 1986;15(5):557–564.
- Ohle R, et al. The Alvarado score for predicting acute appendicitis: a systematic review. BMC Med. 2011;9:139.
- WSES Jerusalem guidelines for diagnosis and treatment of acute appendicitis. World J Emerg Surg. 2020;15:27.
- Di Saverio S, et al. Diagnosis and treatment of acute appendicitis: 2020 update of the WSES Jerusalem guidelines. World J Emerg Surg. 2020;15(1):27.