The collected data included clinical findings (tenderness in RLQ, guarding in RLQ, and body temperature), and symptoms (pain in RLQ, migration of pain, vomiting and anorexia), together with laboratory test results (C-reactive protein (CRP), leukocyte count, proportion of neutrophils), as well as time passed between the onset of symptoms to clinical evaluation. In addition, the surgeons were requested to estimate the probability of appendicitis on clinical basis only with three-step scale: likely, possible, or improbable. Before this estimation, no diagnostic imaging was performed.