CT features of chronic contained rupture of an abdominal aortic aneurysm.

Four cases among the 149 patients who required repair of an infrarenal abdominal aortic aneurysm (AAA) during the last five years, were chronic contained rupture. The first symptom at onset was back pain and physical examination revealed the patients to be in no acute distress. The sites of rupture were posterior in all cases. They were operated through an extraperitoneal approach. There was no operative mortality and all survived. The CT features, (1) discontinuity of the rim of calcification in the true aneurysm wall, (2) well defined soft tissue density adjacent to the aorta, (3) the concealed psoas muscle and the displaced viscera depending on the size of the lesion, and (4) no appearance of contrast material in the hematoma in some cases, led to the correct diagnosis of contained rupture.