CT diagnosis of ruptured abdominal aortic aneurysm

Computed tomography (CT) was performed in six patients with surgically proved ruptured abdominal arotic aneurysms. In all six patients, both abdominal aortic aneurysms and retroperitoneal hematomas, which led to the correct diagnosis of ruptured abdominal arotic aneurysm, were demonstrated by CT scan. In five patients, a retroperitoneal hematoma was seen in the unilateral perirenal space. A hematoma was also noted in the ipsilateral anterior pararenal space in three of these five patients. In the remaining one, a posterior pararenal hematoma was seen in the psoas muscle. In two of four patients (50 %), postcontrast CT showed extravasation of the contrast medium at the actual bleeding site confirmed by surgery. In one of the two, the periaortic fat layer was partially obliterated at the point of extravasation. This partial obliteration of the periaortic fat layer was seen on a pre- or post-contrast CT scan in five of six patients (83 %). The high incidence of the latter finding is especially important because the exact rupture site can be determined without the administration of contrast medium even in the case of renal dysfunction. However, this is not available in the case of a very thin patient because of the poor periaortic fat layer. In conclusion, CT is a most useful modality for the diagnosis of suspected ruptured abdominal aortic aneurysm. (author)