Abdominal aortic aneurysms. Ultrasonic measurement of the transverse diameter and its prognostic significance in the light of pathological observations.

The risk of rupture of an abdominal aortic aneurysm is related to size. Pathological observations suggest that there is usually an asymmetric formation of mural thrombus in the aneurysm sac and that rupture occurs more commonly through the lateral walls where there would be less. Ultrasonic estimation of the transverse diameter of an aneurysm offers a useful clinical method of monitoring size and likelihood of rupture.