Introduction Patients with an acute abdomen are a common presentation for those participating in emergency surgery cover. The aetiology of this presentation incorporates the spectrum of organ systems and is often not identified satisfactorily. Nevertheless, certain diagnoses will always be difficult to make and some presentations can be deceptive. Radiological investigations increasingly play a role in establishing an accurate diagnosis and frequently allow prompt management to be instituted. Patients with an acute abdomen are a common presentation for those participating in emergency surgery cover. The aetiology of this presentation incorporates the spectrum of organ systems and is often not identified satisfactorily. Nevertheless, certain diagnoses will always be difficult to make and some presentations can be deceptive. Radiological investigations increasingly play a role in establishing an accurate diagnosis and frequently allow prompt management to be instituted. Ruptured AAA should be considered as a differential diagnosis in all elderly patients presenting with acute severe abdominal pain who may be haemodynamically stable. Atypical history and examination with inconsistent or equivocal clinical signs should raise the suspicion of aneurysm, particularly in elderly men with known arterial disease. There should be a low threshold for both requesting and justifying definitive imaging (ie CT) in such cases if a catastrophic outcome through misdiagnosis is to be avoided.