In observation group repeated clinical examination is done after 6-8 hours interval with repeated blood test for calculation of Adult Appendicitis Score. Patients with decreasing score value continue observation without imaging, whereas patients with the same score value or higher (but below 16) undergo diagnostic imaging as in other group. Laparoscopy is done without imaging in patients with high score (16 or higher). Antibiotics are not allowed, but prophylactic antibiotics during induction of anesthesia are allowed.