What is the Alvarado Score?
The Alvarado score is a clinical scoring system that combines symptoms, physical examination findings, and laboratory values to stratify patients with suspected acute appendicitis into low, intermediate, and high-risk categories, helping clinicians decide whether to discharge, observe, or proceed with imaging and surgery. 1
Score Components and Calculation
The Alvarado score assigns points from 0 to 10 based on the following criteria 1:
Symptoms (3 points total):
- Migration of pain to right lower quadrant: 1 point
- Anorexia: 1 point
- Nausea/vomiting: 1 point
Signs (3 points total):
- Tenderness in right lower quadrant: 2 points
- Rebound tenderness: 1 point
Laboratory findings (4 points total):
- Elevated white blood cell count >10,000/mm³: 2 points
- Left shift (neutrophilia): 1 point
Risk Stratification and Clinical Interpretation
Low risk (score 0-4): Approximately 5% probability of appendicitis; these patients can be safely discharged without imaging. 1 The score has 99% sensitivity for excluding appendicitis at a cutoff <5, making it excellent for ruling out the diagnosis. 1, 2
Intermediate risk (score 5-6): Approximately 30-36% probability of appendicitis; these patients require imaging (CT scan or ultrasound) for definitive diagnosis. 1 This group lacks diagnostic certainty and benefits most from further evaluation. 1
High risk (score 7-10): 78-98% probability of appendicitis; these patients should proceed to surgery or confirmatory imaging. 1 At a cutoff of 7, the score has 81% specificity overall, though this varies significantly by population. 1
Clinical Performance and Limitations
The Alvarado score performs best as a "rule-out" tool rather than a "rule-in" tool. 2 While it has excellent sensitivity (99%) for excluding appendicitis at low scores, its specificity at high scores is limited (81% overall, only 57% in men, 73% in women, 76% in children). 2
Critical limitations include:
Not sufficiently specific to confirm appendicitis in adults: The World Society of Emergency Surgery recommends against using the Alvarado score alone to positively confirm appendicitis. 3
Poor performance in certain populations: The score is unreliable in differentiating complicated from uncomplicated appendicitis in elderly patients and is less sensitive in HIV-positive patients. 3
Age-related issues: The score is less reliable at extremes of age (0-10 years and 60-80 years). 1 In preschool children, appendicitis often presents with atypical features leading to lower scores even when disease is present. 4
Gender differences: The score over-predicts appendicitis probability in women across all risk strata, while it is well-calibrated in men. 2
Cannot differentiate disease severity: The score cannot distinguish between uncomplicated and complicated (perforated) appendicitis. 3
Recommended Clinical Use
For adult patients: Use the Alvarado score to exclude appendicitis (scores <5) and identify intermediate-risk patients (scores 5-6) who need imaging. However, prefer the AIR (Appendicitis Inflammatory Response) score or AAS (Adult Appendicitis Score) over the Alvarado score, as these have higher discriminating power and better performance. 3
For pediatric patients: The Alvarado score can help exclude appendicitis, but never make the diagnosis based on clinical scores alone—always supplement with imaging and clinical judgment. 3, 4 The AIR score outperformed the Alvarado score in children in comparative studies. 3, 4
For pregnant patients: The score may be falsely elevated due to physiological increases in WBC and frequency of nausea/vomiting, especially in the first trimester. Always request laboratory tests and inflammatory markers; do not rely on symptoms and signs alone. 3
For elderly patients with scores ≥5: Strongly recommend CT scan to confirm diagnosis and distinguish perforated from non-perforated appendicitis, as the score has limited reliability in this age group. 1
Common Pitfalls to Avoid
Do not use the Alvarado score as the sole determinant for surgical intervention—it should be part of a comprehensive diagnostic approach that includes clinical judgment and, when appropriate, imaging. 1
Do not discharge patients with intermediate scores (5-6) without imaging, as approximately one-third of these patients have appendicitis. 1
Do not assume high scores (≥7) always indicate appendicitis, particularly in women and children where the score over-predicts disease. 2
In elderly patients, do not rely on low scores (<5) to exclude serious pathology—these patients should not be discharged without adequate monitoring and consideration of imaging if symptoms persist. 1