Fifteen years of experience using 6 cm as a criterion for abdominal aortic aneurysm surgery

Abstract

Abstract Background One criterion for abdominal aortic aneurysm (AAA) surgery in the authors' unit is aneurysm diameter of 6 cm. The impact of applying this criterion on surgical workload and rupture rate was analysed. Methods Some 584 consecutive patients with an AAA of 3 cm or greater presenting to this unit since 1984 have had the following criteria for considering surgery applied prospectively: a diameter of 6 cm, an expansion rate of more than 1 cm per year, or symptoms. Results Forty-three patients had an AAA of 6 cm or greater on initial presentation and would have been treated in the same way, if a smaller diameter was used. Sixty-eight patients had an AAA that expanded to 6 cm on observation with ultrasonography over the period of up to 15 years. The total number of patients with a 6-cm AAA was therefore 111. Of the 541 aneurysms that were under 6 cm at the initial scan, 454 were followed with ultrasonography. Some 343 reached 4 cm and 204 reached 5 cm. Operating at 5 cm therefore would have doubled the potential workload, and 4 cm would have tripled it. During the 15 years, 24 (4 per cent) of the 584 AAAs ruptured. Of these 24 patients, 12 were unfit for surgery, five declined operation or follow-up, the aneurysm ruptured beforehand in three who were booked for an operation or outpatient visit, and four failed to reach the operative criteria before rupture occurred. Rupture could therefore possibly have been prevented in seven (1 per cent) of the 584 by operating at a smaller diameter. The reported mortality rate for planned surgery is 2–8 per cent. Conclusion By using these criteria for surgery, the workload is cut by half or more and the consequent risk of rupture is lower than the mortality rate associated with planned surgery.