Long Term Growth and Rupture Risk, and Associated Factors of Splenic Artery Aneurysms in a Large Observational Cohort

The aim of this retrospective observational study was to analyse imaging and patient related parameters of splenic artery aneurysms (SAAs) and their impact on SAA growth and rupture.

The term aneurysm was systematically searched for in the radiology reports of 1.9 million abdominal imaging studies conducted in a university hospital district between 2006 and 2020. Clinical data were collected from the medical records and causes of death from a registry. Computed tomography scans were reviewed for radiological parameters. Multivariable tests were used to analyse factors associated with SAA growth and rupture.

Eight hundred and twenty-one SAAs in 670 patients were identified from 35 378 radiology reports containing the term aneurysm. The mean SAA diameter ± standard deviation at presentation was 14.1 ± 5.6 mm. Follow up imaging was available for 584 SAAs (71.1%), with a mean follow up of 79.2 ± 54.0 months. Growth was observed in 77 (13.2%) of these SAAs. The mean growth rate was 0.097 ± 0.50 mm/year, and 0.73 ± 1.22 mm/year in growing SAAs. Three SAAs (0.4%) ruptured at a mean size of 32 mm. Aneurysm wall calcification was independently associated with decreased risk of SAA growth or rupture: mild calcification (odds ratio [OR] 0.28, 95% confidence interval [CI] 0.12 - 0.67; p = .004), over one third circular calcification (OR 0.16, 95% CI 0.06 - 0.43; p< .001), and full circumference, i.e., eggshell calcification (OR 0.05, 95% CI 0.02 - 0.16; p < .001). Aneurysm location at the splenic hilum was also associated with decreased growth and rupture risk (OR 0.43, 95% CI 0.22 - 0.85; p = .015), while presence of abdominal aortic aneurysm (AAA) was associated with increased risk (OR 8.08, 95% CI 1.08 - 60.30; p = .042).

Most SAAs remained stable in size, with only a few ruptures occurring over a mean follow up of 6 years. Aneurysm wall calcification and SAA location at the splenic hilum were associated with a decreased risk of growth and rupture, while the presence of AAA was associated with increased risk.