Teaching Case

The patient was admitted to our hospital in shock state. He was brought by relatives reporting a history of abdominal aortic aneurysm. He immediately underwent a CT examination documenting a ruptured large abdominal aortic aneurysm. The patient was taken directly to the operating department and a surgical abdominal aortic aneurysm repair was performed; now the patient is out of danger.

Abdominal aortic aneurysms (AAA) usually occur in the setting of atherosclerotic disease but may be caused by syphilis, by extension of a dissection from above, or by connective tissue disorders (i.e. Takayasu's arteritis). Complications of abdominal aortic aneurysm include peripheral embolization, thrombosis and infection, but rupture is one of the most feared complications confronted by cardiovascular surgeons because it is usually catastrophic (about 40% of patients with ruptured AAA die before admission to the hospital; the next 40-50% of patients who reach a hospital die in the perioperative period or within 30 days after surgery). The incidence of rupture increases with increasing aneurysm size above 4 cm. Rupture usually occurs into the left retroperitoneal space and rarely into the gastrointestinal tract or inferior vena cava. If a ruptured aneurysm is suspected, a CT examination of the abdomen should be done with contrast enhancement. Typical findings include obscuration or anterior displacement of the aneurysm by an irregular high density mass or collection that extends into one or both perirenal spaces. The wall of the aneurysm may be identified by calcifications while the lumen enhances. Other findings include anterior displacement of the kidney by hematoma, enlargement or obscuration of the psoas muscle, and a focally indistinct aortic margin that corresponds to the site of rupture. In contrast, a chronic pseudoaneurysm appears as a well-defined, ususally round mass with attenuation similar or lower than that of the native aorta on noncontrasted images.