Appendicitis: Test and Diagnosis

Laboratory parameters of the 1st order – obligatory laboratory tests.

  • Small blood count
  • Differential blood count
  • Inflammatory parameters – CRP (C-reactive protein) or ESR (erythrocyte sedimentation rate).
  • Urine status (rapid test for: pH, leukocytes, nitrite, protein, glucose, ketone, urobilinogen, bilirubin, blood), sediment.

Laboratory parameters 2nd order – depending on the results of the history, physical examination, etc. – for differential diagnostic clarification.

Appendicitis inflammatory response (AIR) score and Alvarado score

Clinical findings/laboratory parameters Alvarado score AIR score
  • Nausea
 1
Nausea or vomiting 1
Loss of appetite 1
Right lower quadrant pain 2 1
Pain migration to the right lower quadrant 1
Pressure pain or muscular defensive tension 1
  • Light
 1
  • Medium
 2
  • Strong
 3
Body temperature > 37.5 °C 1
  • Body temperature > 38.5 °C
 1
Leukocytosis (increase in the number of white blood cells/leukocytes) 1
Neutrophil granulocytes
  • 70-84 %
 1
  • ≥ 85 %
 2
Leukocytes (SI units)
> 10.0 × 109/l 2
  • 10.0-14.9 × 109/l
 1
  • ≥ 15.0 × 109/l
 2
CRP concentration (inflammation parameter)
  • 10-49 g/l
 1
  • ≥ 50 g/l
 2
Total score 10 12

Assessment

  • Alvarado score: sum 0-4 = not likely, sum 5-6 = unclear result, sum 7-8 = likely, sum 9-10 = very likely.
  • AIR score: sum 0-4 = low probability/low risk, sum 5-8 = moderate to high risk, sum 9-12 = high probability.

According to Scott et al, the AIR score correctly classifies most patients with nonappendicitis-related pain into the low-risk group while maintaining high sensitivity (percentage of diseased patients in whom disease is detected by use of the test, i.e., a positive test result occurs) for all appendicitis cases. The following are the results in detail:

  • AIR score* of at least 5 points detected appendicitis with a sensitivity of 90%, advanced stages even with a sensitivity of 98%. Specificity (= proportion of correctly detected patients without appendicitis) 63%; i.e., the negative predictive value was thus 94%.
  • If the AIR score reached at least 9 points: Specificity (probability that actually healthy people who do not have the disease in question are also detected as healthy in the test) at 97%;Cave! Most appendicitis patients have already had a perforation (“breakthrough”) or gangrene. A An AIR score below 5 correctly identified 63% of patients who did not have appendicitis.

Sonography (ultrasound) was not likely to detect appendicitis in the low-risk range (AIR score: sum of 0 to 4); however, in the intermediate-risk range, sonography was able to help detect appendicitis. Conclusion (of authors):

  • Patients in the low-risk range (AIR score: sum 0 to 4): patient education/counseling on appendicitis risk and discharge – readmission if symptoms increase; on readmission computed tomography of the abdomen (CT abdomen): discharge if no findings.
  • Patients with intermediate AIR risk: sonography:
    • If the result is positive: surgery
    • In case of unclear or negative result: CT abdomen
  • Patients in high-risk area: surgery; if imaging is done, it should be a CT abdomen