Aortic Bulge: A Possible Predictive Sign of Impending Aortoenteric Fistula

The purpose of this study is to introduce the aortic bulge sign, a finding observed retrospectively on computed tomography prior to the acute presentation of aortoenteric fistula, and to determine its interobserver reliability.

Following research ethics board approval, all cases of aortoenteric fistula at our institution occurring from 2011-2015 were identified retrospectively. All previous computed tomography images of patients who eventually developed aortoenteric fistula were reviewed by a single observer for the presence of a potentially predictive finding of fistulization, the aortic bulge sign. These previous images were then combined with age and sex matched controls into a case bank. Eight radiology residents and staff were instructed in observing the aortic bulge sign. These observers then reviewed the case bank in a blinded analysis to determine the interobserver reliability of this finding.

Fourteen cases of aortoenteric were identified. The average patient age was 70.71 years with a male-to-female ratio of 11:3. Eleven patients had previous computed tomography images available for review. With blinded analysis by multiple observers, the aortic bulge sign was identified with greater than 80% agreement in six of 11 cases (66.67%). Fleiss' kappa was calculated at k = 0.60 (95% confidence interval 0.50-0.69), corresponding to moderate-to-substantial interobserver agreement.

The aortic bulge sign has been retrospectively identified as a promising computed tomography finding of eventual aortoenteric fistula prior to acute presentation. Further study is required to determine the diagnostic value of this sign.