[Retroperitoneal vascular emergencies].

Ruptured abdominal aortic aneurysm is the major surgical emergency in the retroperitoneal compartment. Rupture of an abdominal aortic aneurysm is always fatal without urgent operative repair. Computed tomography is the reference standard for the diagnosis of ruptured abdominal aortic aneurysm in hemodynamically stable patients. At CT, the diagnosis is based on the combination of abdominal aortic aneurysm and extraluminal retroperitoneal blood. Retroperitoneal hemorrhage usually demonstrates both isodense and hyperdense areas. In most cases hemorrhage is located in psoas compartments and perirenal space. In the case of ruptured abdominal aortic aneurysm other findings may be demonstrated such as focal interruption of the aortic wall and active extravasation of contrast media in the retroperitoneal compartments. Inflammatory abdominal aortic aneurysm, that may present as acute abdominal pain, should be recognized and differentiated from ruptured abdominal aortic aneurysm. Inflammatory abdominal aortic aneurysm is characterized by a fibrotic process around the abdominal aorta that may entrap adjacent structures such as ureters, duodenum and inferior vena cava. Aortic dissection, mycotic aneurysm, and inferior vena cava thrombosis are less common. Complications occurring after emergency aneurysm replacement are also considered.