Classic history in less than 60% of cases! Retrocaecal in 15% so hip pain (psoas irritation), flank or right upper quadrant pain/symptoms. A deep appendix tip can give rectal pain especially on defaecation, plus diarrhoea, dysuria!

Under 6 with 48+hr symptoms are likely to have appendicitis.

Periumbilical pain due to T10 innervation, then localises to RIF as serosa involved. But can be suprapubic if appendix lies medially, or flank pain if lateral.

Vomiting at start unusual except retrocaecal, tends to start later.

Fever low grade or absent.

Under 5 can just present with diffuse pain and peritonitis as omentum under developed, so fails to contain. Higher risk of delayed diagnosis, perforation.

To check for psoas irritation, hyperextend hip (lie on side). For obturator, flex hip and internally rotate.

Speed bump sign good positive predictive sign!

Investigations

WCC/CRP poor sens/spec especially in first 24hrs.

USS – hyperechoic mesenteric fat, fluid collection, local dilated loop suspicious if appendix cannot be seen. 90-95% sens/spec.