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A lady in her late 70's attends the ED with generalised abdominal pain, worse centrally, all day. She is obese and has multiple co-morbidities - including a history of constipation, hypertension, Type 2 diabetes and two NSTEMI. She has an abdo XR performed at the request of the surgical team and is later discharged with a diagnosis of constipation, after the pain improved with analgesia. What does the XRay show?  It appears to show an 8cm aortic aneurysm, outlined by the calcified wall of the aorta. Studies published in the 1980s and 1990s demonstrated that, among elderly patients presenting to the ED with abdominal pain, at least 50% were hospitalized and 30-40% eventually had surgery for the underlying condition. These studies also showed that approximately 40% of these patients were misdiagnosed, contributing to an overall mortality rate of approximately 10%. The only studies published since the widespread use of advanced imaging showed that nearly 60% were hospitalized, and, in the following 2 weeks, 20% underwent surgery and 5% died. Many elderly patients have a diminished sensorium, allowing pathology to advance to a dangerous point prior to symptom development. Elderly patients with acute peritonitis are much less likely to have the classic findings of rebound tenderness and local rigidity. They are less likely to have fever, leukocytosis, or elevated C-reactive protein level. In addition, their pain is likely to be much less severe than expected for a particular disease. Numerous studies have demonstrated low sensitivity and accuracy for plain abdominal radiography in the evaluation of acute abdominal pain as well as various specific diseases such as perforated viscus, bowel obstruction, ingested foreign body, and ureteric stones. In contrast, emergency ultrasound had a sensitivity of 96.3% , a specificity of 100% ; a negative predictive value of 98.6% and positive predictive value of 100% (95% CI 86.8% to 100%) for the detection of AAA. In this case, her ultrasound was actually normal!  The indications for a plain abdo film are now limited and our own Prof has written a paper clearly defining them. 
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