A ruptured abdominal aortic aneurysm request is one of the 'hottest' cases you will have on your CT scanner in terms of need for speed.
Far more common in males, it typically presents with back pain and hypotension.
A non-contrast CT is really all that is required in an emergency to identified free retroperitoneal blood and the aneurysm. However, contrast is given by many.
As well as the aneurysm itself - typically with internal thrombus and wall calcification the key finding is Retroperitoneal hemorrhage adjacent the aneurysm. Peri-aortic blood may extend into adjacent spaces like the perirenal or pararenal spaces or less commonly intra-peritoneal extension.
The retroperitoneal free fluid HU can be measured if reassurance is required that it is blood.