Assessment of abdominal aortic aneurysm size.

Because of the importance of size in the decision for elective operation in patients with abdominal aortic aneurysm (AAA) and the need to identify accurately even small aneurysms, a prospective study was carried out to compare currently available diagnostic methods. A series of 78 patients with AAA underwent evaluation by physical examination, lateral lumbar spine X-ray, aortic ultrasound, and aortography. Measurements were compared to aneurysm size at operation. Physical examination was most variable, and tended to overestimate size by approximately 20%. Lateral spine X-ray was useful in three of every four patients and in these cases it was reliable and reasonably accurate. Ultrasonography was most widely applicable and very reliable for diagnosis. Its tendency to underestimate aneurysm size in our experience may be improved by use of gray-scale units, which better define aneurysm wall thickness. The anatomic information provided by aortography was of great value in the surgical management of patients with AAA, but aortography was of limited value in accurate measurement and should not be employed for this purpose.