Few internal iliac artery aneurysms rupture under 4 cm.

OBJECTIVE: This study investigated the diameter of internal iliac artery (IIA) aneurysms (IIAAs) at the time of rupture to evaluate whether the current threshold diameter for elective repair of 3 cm is reasonable. The prevalence of concomitant aneurysms and results of surgical treatment were also investigated.

METHODS: This was a retrospective analysis of patients with ruptured IIAA from seven countries. The patients were collected from vascular registries and patient records of 28 vascular centers. Computed tomography images taken at the time of rupture were analyzed, and maximal diameters of the ruptured IIA and other aortoiliac arteries were measured. Data on the type of surgical treatment, mortality at 30 days, and follow-up were collected.

RESULTS: Sixty-three patients (55 men and 8 women) were identified, operated on from 2002 to 2015. The patients were a mean age of 76.6 years (standard deviation, 9.0; range 48-93 years). A concomitant common iliac artery aneurysm was present in 65.0%, 41.7% had a concomitant abdominal aortic aneurysm, and 36.7% had both. IIAA was isolated in 30.0%. The mean maximal diameter of the ruptured artery was 68.4 mm (standard deviation, 20.5 mm; median, 67.0 mm; range, 25-116 mm). One rupture occurred at <3 cm and four at <4 cm (6.3% of all ruptures). All patients were treated, 73.0% by open repair and 27.0% by endovascular repair. The 30-day mortality was 12.7%. Median follow-up was 18.3 months (interquartile range, 2.0-48.3 months). The 1-year Kaplan-Meier estimate for survival was 74.5% (standard error, 5.7%).

CONCLUSIONS: IIAA is an uncommon condition and mostly coexists with other aortoiliac aneurysms. Follow-up until a diameter of 4 cm seems justified, at least in elderly men, although lack of surveillance data precludes firm conclusions. The mortality was low compared with previously published figures and lower than mortality in patients with ruptured abdominal aortic aneurysm.