The typical symptoms of acute appendicitis include abdominal pain, which starts in the upper abdomen or around the navel and, after several hours, shifts and localizes to the lower right abdomen. Additionally, reflexive gastric spasms may cause nausea and vomiting. Due to the inflammation, the body may develop a fever, generally not exceeding 38 degrees Celsius. If the inflammation affects the parietal peritoneum, it can cause tenderness, rebound pain, and abdominal muscle rigidity. These are the typical symptoms, and a preliminary diagnosis can usually be made based on them. Most cases require an appendectomy.