European Journal of Emergency Medicine vol:7 issue:1 pages:25-30
Computed tomography (CT) and ultrasonography (US) have been proposed as non-invasive diagnostic aids in patients with suspected acute appendicitis. Currently, clear guidelines about the indications to use these techniques are lacking. Using the concepts of decision analysis, a model was created to calculate the effectiveness of US and CT in patients with clinically suspected appendicitis. The perspective chosen was the health of individual patients. The model makes use of published data and provides a critical threshold probability (ctp). Decisions in individual cases can be made by comparing ctp with the clinical probability of disease. The calculated ctp-values for US and CT were 0.58 and 0.74, respectively. In other words, on average, US (CT) is indicated only if the expert clinician considers the probability of disease to be smaller than 58% (74%). It is concluded that in patients with suspected acute appendicitis, selective rather than routine use of imaging studies is recommended. The exact value of the decision threshold should be determined in function of the local situation.