Incidental abdominal aortic aneurysms are largely undocumented and unmonitored.

Background: In countries without organized population screening, incidental detection remains the major form of abdominal aortic aneurysm (AAA) diagnosis. Despite the presumed homogeneity in AAA prevalence, its rate of repair is highly variable, with Portugal treating 2 to 6 times fewer AAA per habitant than other western countries.

Objectives: To evaluate the detection rate and monitoring of incidental AAA in a multicentre cohort from Portuguese hospitals.

Methods: All abdominal CT scans performed in men ≥ 65 years old in three major Portuguese hospitals between January and June 2018 were selected for review. CT scans prescribed by the Vascular Surgery or Emergency Departments were excluded. Patients with previously known AAA were also excluded. Subjects with newly detected aneurysms were assessed for the two primary outcomes: the description of the finding by the radiologist in the written report; the effective follow-up recommendations by the prescriber of the CT or by the general practitioner (GP). Patients with newly found AAA that met criteria for monitoring or treatment and failed to be given guidance were contacted and included in surveillance programs.

Results: Overall, 3292 abdominal CT scans were selected for review. A total of 133 newly found aneurysms were detected (4.2% prevalence in the cohort). Of those, 48 cases (36%) were not described by the radiologist in the written report. Further 42 patients (32%) were not successfully oriented by the ordering physician or GP, despite having had their AAA mentioned. Overall, only 32% (n = 42) of the newly diagnosed AAA were correctly identified and referred to monitoring.

Conclusions: Incidental AAA is a common occurrence in in-hospital abdominal CTs. A significant number is not documented by the radiologist and the vast majority is not referred to monitoring. This could be a major reason for the low elective treatment rate of AAA in Portugal.