Purpose: The purpose of this study was to establish ultrasonographic criteria for the normal size of the abdominal aorta and iliac arteries in patients without vascular disease.
Methods: The luminal diameters of the proximal and distal abdominal aorta and the common iliac arteries were measured by ultrasonography in 160 patients (15 to 89 years) who were without known vascular disease.
Results: In patients above 50 years of age the distal aorta, which most often is involved in aneurysmatic dilations, measured 16.8 +/- 2.9 mm in men and 14.6 +/- 1.9 mm in women (p < 0.001). The diameter of the iliac artery in these patients was 10.1 +/- 2.0 mm in men and 9.2 +/- 1.3 mm in women (p < 0.001). The usually present gradual narrowing of the aorta toward the bifurcation was replaced by a slight increase (1 to 2 mm) in 5% of the men and 6% of the women. Focal areas of aortic enlargement, however, were not observed. In multivariate analysis, including age, height, body weight, and sex, the distal aortic diameter was significantly correlated only to age (r = 0.46; p < 0.001) and sex (r = -0.29; p < 0.001). With aging the mean of the proximal and distal aortic diameters increased by 0.08 and 0.05 mm/yr, respectively. Also correlated with age was a linear reduction in systolic expansion (r = -0.73; p < 0.001).
Conclusions: Enlargement of the distal aorta and common iliac artery should be considered when (1) the luminal diameters in men exceed 23 and 14 mm, respectively, and in women 19 and 12 mm, respectively, (2) the ratio of the proximal and distal aortic diameter exceeds 1.1, and (3) there is demonstration of focal enlargement.