Criteria

Use a scoring system in adults to determine the likelihood or rule out the diagnosis of appendicitis in order to guide further investigations and management.[7]

  • Use either the Appendicitis Inflammatory Response (AIR) or the Adult Appendicitis Score (AAS) to determine whether your patient is at high, intermediate or low risk of having appendicitis.[7]

    • High-risk patients who are aged <40 years, and have strong symptoms and signs of appendicitis, may go straight to surgery without imaging.[7] However, check your local protocols as this varies in practice. 

    • Intermediate-risk patients may undergo further imaging and observation.[7]  

    • Low-risk patients may be safely discharged without diagnostic imaging, as long as they have appropriate safety-netting.[7]

  • The Alvarado score can be used to rule out appendicitis but do not use it to positively confirm a diagnosis of appendicitis; it is not specific enough for that purpose.[7]

  • All the scoring systems involve a combination of history, examination findings, and investigation results.[7]

  • These scoring systems should not be used in place of cross-sectional imaging to make a diagnosis of appendicitis in elderly patients owing to limited evidence in this patient group.[4]​[5]​

In children, do not make the diagnosis of appendicitis based on clinical scores alone.[7] Children frequently have atypical clinical features and obtaining a reliable history can be challenging. Clinical scores are useful tools in excluding acute appendicitis in children. The diagnosis of acute appendicitis in children should be made on the basis of clinical suspicion, blood tests, and, if needed, imaging (see the Investigations section).

Use the following table to calculate the score for your patient, depending on which scoring system you are using:[40][41] 

AIR[40]

AAS[41]

Alvarado*[40][42]

PAS*[43]

History

Vomiting

1 point

N/A

1 point for either vomiting OR nausea

1 point for either vomiting OR nausea

Anorexia

N/A

N/A

1 point

1 point

Pain in right lower quadrant

1 point

2 points

2 points

N/A

Migration of pain to the right lower quadrant

N/A

2 points

1 point

1 point

Examination

Right lower quadrant tenderness

N/A

  • Women aged 16-49: 1 point

  • Women aged ≥50 and men: 3 points

N/A

2 points for right lower quadrant tenderness to cough, percussion, or hopping

Right iliac fossa tenderness

N/A

N/A

N/A

2 points

Rebound tenderness or guarding

  • Light: 1 point

  • Medium: 2 points

  • Strong: 3 points

  • Mild: 2 points

  • Moderate or severe: 4 points

1 point

N/A

Fever

>38.5℃: 1 point

N/A

>37.3℃: 1 point

>38.0℃: 1 point

Blood test results

Leukocytosis shift

N/A

N/A

1 point

N/A

Proportion of neutrophils

  • <70: 0 points

  • 70-84: 1 point

  • ≥85: 2 points

  • <62: 0 points

  • ≥62 and <75: 2 points

  • ≥75 and <83: 3 points

  • ≥83: 4 points

N/A

N/A

Absolute neutrophil count

N/A

N/A

N/A

>7500: 1 point

White blood cell count (× 109/L)

  • <10.0: 0 points

  • 10.0–14.9: 1 point

  • ≥15.0: 2 points

  • <7.2: 0 points

  • ≥7.2 and <10.9: 1 point

  • ≥10.9 and <14.0: 2 points

  • ≥14.0: 3 points

  • ≤10: 0 points

  • >10: 2 points

  • >10: 1 point

C-reactive protein (mg/L)

  • <10: 0 points

  • 10–49: 1 point

  • ≥50: 2 points

Symptoms <24 hours

  • <4: 0 points

  • ≥4 and <11: 2 points

  • ≥11 and <25: 3 points

  • ≥25 and <83: 5 points

  • ≥83: 1 point

Symptoms >24 hours

  • <12: 0 points

  • ≥12 and <152: 2 points

  • ≥152: 1 point

N/A

N/A

Add up the total number of points for your patient to calculate the risk of appendicitis as follows:[40][41]

High risk

  • AIR: 9-12 points

  • AAS: ≥16 points

  • Alvarado: 9-10 points

  • PAS: ≥7 points

Intermediate risk

  • AIR: 5-8 points

  • AAS: 11-15 points

  • Alvarado: 5-8 points

  • PAS: 4-6 points

Low risk

  • AIR: 0-4 points

  • AAS: 0-10 points

  • Alvarado: 0-4 points

  • PAS: <4 points

*In children, do not make the diagnosis of appendicitis based on clinical scores alone.[7] Children frequently have atypical clinical features and obtaining a reliable history can be challenging. Clinical scores are useful tools in excluding acute appendicitis in children.[7] 

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