Late results of small untreated abdominal aortic aneurysms.

We report our experience with 73 patients who were initially selected for nonoperative management of an abdominal aortic aneurysm less than 5 cm in diameter. Size of the aneurysm was determined by ultrasound (34); arteriography (16); computerized tomography (17); plain x-ray (4); and magnetic resonance imaging (2). End points of the study were subsequent elective resection, rupture, death from cause other than rupture, or an intact aneurysm followed for a minimum of three years. Overall, 28 (38%) aneurysms were subsequently resected on an elective basis; four (5%) ruptured; 15 (21%) were intact at the time of the patient's death; and 26 (36%) remained intact during follow-up of 3 to 6.5 years. Indications for elective resection were aneurysm enlargement (21); symptoms suggesting impending rupture (3); and improvement in medical condition (4). In the 43 aneurysms initially less than 4 cm diameter, 16 (37%) had elective resection and one (2%) ruptured, and in the 30 that were 4-4.9 cm, 12 (40%) were resected and three (10%) ruptured. The four aneurysms that ruptured had enlarged to greater than 5 cm prior to rupture. We conclude that aneurysms less than 4 cm can be safely followed. Aneurysms 4-4.9 cm should be considered for operation, depending upon the size of the aneurysm, patient's life expectancy, and risk factors for surgery. Any aneurysm that enlarges should be resected, especially if the aneurysm becomes larger than 5 cm in diameter.