Objective: To delineate the natural history of infrarenal aortic aneur
ysms with respect to growth rate. Methods: A referral based series of
233 patients with abdominal aortic aneurysm teas serially assessed by
abdominal ultrasound. Results: The mean age was 71 years and the media
n follow zip 26 months (range 6-146). The mean growth rate of the seri
es was 3.2 mm/year. Division of the initial size into those less than
41 mm (128 patients), between 41-60 mm (92 patients) and those above 6
0 mm (13 patients) in AP diameter showed mean growth rates per year we
re 2.6 mm/year, 4.1 mm/year and 6.5 mm/year. Examination of the relati
onship between aneurysm size and subsequent growth rate over the whole
study period revealed a rank correlation of 0.19 (p = 0.002). Aneurys
ms were also observed to expand at an erratic rare both in terms of ti
me and size. Conclusions: When the initial decision is to observe the
patient, serial ultrasound examinations facilitate later judgements on
the balance of risks in relation to surgical treatment.