The Natural History of Splenic Artery Aneurysms: Factors That Predict Aneurysm Growth

Purpose: To examine the natural history of splenic artery aneurysms (SAAs) at a single institution and assess the effect of patient factors and aneurysm characteristics on aneurysm growth. Materials and Methods: This single-center retrospective study included patients with SAAs who underwent serial imaging over 30 years (1990–2020). Data regarding patient demographics and aneurysm characteristics were collected. The variables contributing to aneurysm growth were assessed using nonparametric tests for continuous variables and chi-square test for categorical variables. Multivariable linear regression was performed using aneurysm growth rate as a continuous dependent variable. Results: A total of 132 patients were included in this study. The median maximum diameter of the SAAs was 15.8 mm (range, 4.0–50.0 mm). Growth over time was observed in 39% of the aneurysms, whereas the remaining 61% were stable in size. Of aneurysms that increased in size, the median aneurysm growth rate was 0.60 mm/y (range, 0.03–5.00 mm/y). Maximum aneurysm diameter of >2 cm and the presence of >50% mural thrombus were significant positive predictors for aneurysm growth (P = .020 and P = .022, respectively). Greater than 50% rim calcification was a significant negative predictor for aneurysm growth (P = .009) in multivariate analysis. Conclusions: A larger baseline SAA size, presence of mural thrombus, and lack of rim calcification are associated with increased aneurysm growth rate.