8.1 Study parameters/endpoints 8.1.1 Main study parameter/endpoint The main endpoint of the study is to reduce the negative appendectomy rate with 50%. The gold standard is the histological examination by the pathologist. The pathologist considers the appendix as inflamed when at least (local) ulceration with infiltration of polymorphonuclear neutrophils into the mucosa and submucosa (endo-appendicitis) is present, either or not in combination with transmural inflammation, necrosis, perforation and peri-appendicular inflammation. In case of inflammation without mucosal ulceration was found, the contralateral part of the appendix and more transverse slices were examined. [4] An appendix is considered as normal when no signs of inflammation are found and when no other abnormality is found like more rare entities as carcinoid, adenocarcinoma of the appendix or a parasite infection.