A 19-year-old male presents to the ED with 24 hours of abdominal pain that was initially central but is now localised to the right iliac fossa. The patient is generally unwell with fever, malaise and anorexia. On exam, there is guarding. Observations show T 37.8oc, HR 104, BP 112/76, RR 24, SO2 97%. You make a clinical diagnosis of appendicitis.