Imaging review of aortic fistulas.

Aortic fistulas represent rare but life-threatening communications between the aorta and the adjacent structures, most commonly the gastrointestinal tract. They are classified as primary, arising spontaneously in the setting of a native, diseased aorta, or secondary to prior aortic surgery or endovascular repair. Clinical presentation is often variable and nonspecific-ranging from gastrointestinal bleeding, sepsis, abdominal pain to hemodynamic collapse-making imaging pivotal for diagnosis. Computed tomography angiography is the preferred imaging modality. Imaging features such as visualization of the fistula tract and active contrast extravasation into the fistulized hollow organ are definitive signs of aortic fistulas, but are rarely encountered. On the contrary, nonspecific indirect imaging features such as loss of fat planes and/or ectopic foci of gas are more frequently seen. Prompt recognition of these indirect imaging features is crucial, as delayed diagnosis significantly increases mortality. This review article summarizes the types, clinical features, and imaging findings of aortic fistulas, emphasizing the radiologist's pivotal role in timely detection and management of aortic fistulas.