Appendicitis: Diagnostic Tests

Obligatory medical device diagnostics.

  • Abdominal ultrasonography (ultrasonography of abdominal organs).
    • Indications of appendicitis:
      • “Shooting target figure” (diameter > 6 mm) with anechoic mesh cap.
      • Diameter (between longitudinal muscles and serosa) > 6 mm + echogenic environmental responseIn one study, children in whom the external diameter of the appendix was ≥ 7 mm had more than a 9-fold higher risk (odds ratio [OR]: 9.4]) of having acute appendicitis compared with children with smaller diameters.
    • Evidence for perforation:
      • Abolition of wall differentiation, esp. absence of echo-rich submucosa (= double-layered).
      • Inflammatory conglomerate
      • Abscess formation (formation of an encapsulated pus cavity)
      • Echogenic free fluid
      • Paralytic ileus (intestinal obstruction due to intestinal paralysis).

    Note: Color-coded Doppler sonography (FKDS) may help visualize hyperemia of the appendiceal wall. Notice: In a meta-analysis, abdominal ultrasonography for suspected appendicitis achieved a sensitivity of only 69% (percentage of diseased patients in whom the disease is detected by use of the procedure, i.e., a positive finding occurs) and a specificity of 81% (probability that actually healthy individuals who do not have the disease in question are also detected as healthy by the test).

Optional medical device diagnostics – depending on the results of the history, physical examination, laboratory diagnostics and obligatory medical device diagnostics – for differential diagnostic clarification.

  • Computed tomography (CT) of the abdomen (abdominal CT) – if perforation of the appendix is suspected; the following signs are most notable:
    • Appendix thickened
    • Surrounding fatty tissue changed inflammatory
    • Appendicolith (fecal stones) in the appendix appendix (visible in up to 40% of cases).
  • Magnetic resonance imaging of the abdomen (abdominal MRI) – indicated especially when sonography (ultrasound examination) is insufficient in young people or pregnant women; good representation of complications.

Pediatric Appendicitis Score (PAS)

Feature Score
Loss of appetite 1
Nausea or vomiting 1
Pain migration to the right lower quadrant 1
Fever ≥ 38 °C 1
Maximum defensive voltage in the lower right quadrant 2
Pain in right lower quadrant on hopping, coughing, or percussion (palpating exam) 2
Leukocytosis ≥ 10,000/mm3 1
Neutrophils ≥ 75% 1

Evaluation of the risk of appendicitis:

  • Score 0-3 = low risk
  • Point value 4-6 = medium risk
  • Point value 7-10 = high risk

Below, sonography results (negative, positive, equivocal appendicitis findings) are presented in relation to their prediction of appendicitis (in %) in combination with PAS scores.

PAS values/risk Negative sonography Positive sonography Doubtful sonography
Low risk 100 % 73 % 9 %
Medium risk 94 % 90 % 13 %
High risk 81 % 97 % 47 %

Conclusion:

  • Children at high risk according to PAS score and negative sonography must be carefully monitored
  • Children at intermediate or high risk and positive sonography are candidates for appendectomy
  • Children at intermediate risk according to PAS score and negative or equivocal sonography require observation