Non-visualized aorta in abdominal aortic aneurysm screening: Screening outcomes and the influence of subject and programme characteristics

Objectives To compare abdominal aortic aneurysm screening outcomes of men with non-visualized aorta at original scan with subsequent scans and to determine predictors of non-visualized aorta. Methods In the Northern Ireland Abdominal Aortic Aneurysm screening programme, outcomes (discharge, annual surveillance, three-monthly surveillance, or vascular referral) and patient and programme characteristics (age, deprivation quintile, family history, technician experience, and screening location) for men with non-visualized aorta were investigated at original scan, and first and second rescans. Results Non-visualized aorta proportions were 2.9, 11.4, and 4.7% at original, first, and second rescan, respectively. There were no differences in screening outcomes between scanning stages (98.4, 97.6, and 97.4% <3 cm). There were 42 men (0.13%) with aortas ≥5.5 cm at original scan, but none at first and second rescan. A significantly greater proportion with non-visualized aorta were from more deprived (5.0%) than less deprived areas (1.7%). Deprivation quintile and staff role were significant independent non-visualized aorta predictors at original scan, and staff role at first rescan. Men from less deprived areas were three times as likely to have aortas visualized than those from more deprived areas (OR = 3.0, CI = 2.4–3.8) at original scan. A man scanned by screening technician compared with lead sonographer was 51% less likely to have aorta visualized at original scan and 94% less likely at first rescan. Conclusions The risk of abdominal aortic aneurysm in men with non-visualized aorta on first or subsequent rescans is no more than for those with visualized aorta on original scanning. Men from deprived areas are much more likely to have non-visualized aorta at original scan.