Screening and surveillance is paramount in the management of small abdominal aortic aneurysms (AAA). Gaps in surveillance after early diagnosis may lead to unrecognized AAA growth, rupture, and death. This study investigates the prevalence and factors associated with rupture of previously diagnosed AAA. Data were extracted from Medicare claims for patients who underwent AAA repair from 2006 to 2009. All relevant preoperative abdominal imaging examinations were tabulated 5 years before AAA repair. Repair for ruptured AAA was compared with repair for intact AAA for those with early diagnosis, which was defined as at least one image more than 6 months before surgery. Gaps in surveillance were defined as no image ≤1 year of surgery or no imaging for >2-year time span. Hierarchic logistic regression was used to examine independent predictors of rupture despite early diagnosis. Of 15,770 patients who underwent AAA repair, 1272 (8.1%) had repair after rupture. Of those with ruptured AAA, 34.7% had abdominal imaging >6 months before rupture, compared with 61.1% for intact repair. For patients with early diagnosis, those with ruptured AAA were older (80.2 ± 6.9 vs 77.6 ± 6.2 years, P < .0001), received fewer images before repair (5.7 ± 4.1 vs. 6.5 ± 3.5, P = .0001), were less likely to be treated in a high-volume hospital (45.4% vs 59.5%, P < .0001), and were more likely to have had gaps in surveillance (47.4% vs 11.8%, P < .0001) compared with those with intact repair. After adjusting for medical comorbidities, gaps in surveillance remained the strongest predictor of rupture by multivariate analysis (odds ratio, 5.97; 95% confidence interval, 4.77-7.48; P < .0001; Table).Tabled 1Predictors of rupture despite early diagnosis adjusted for race, teaching hospital status, medical comorbidity, and year of repairVariableOR (95% CI)PFemale sex1.12 (0.88-1.43).36Age at repair (per decade)1.65 (1.36-1.98)<.0001Gaps in surveillance5.97 (4.77-7.48)<.0001Hospital AAA volume Low2.60 (1.41-4.81).002 High0.68 (0.54-0.86).002 Moderate1.00 (Ref)…Rural residence1.14 (0.89-1.44).3Medicaid-eligible1.37 (0.93-2.00).12Congestive heart failure0.94 (0.57-1.53).79Chronic lung disease0.86 (0.67-1.10).22Diabetes0.64 (0.043-0.96).03Cancer1.04 (0.52-2.10).91AAA, Abdominal aortic aneurysm; CI, confidence interval; OR, odds ratio. Open table in a new tab AAA, Abdominal aortic aneurysm; CI, confidence interval; OR, odds ratio. Despite early diagnosis of AAA, many operative candidates go on to rupture before repair. Improved mechanisms for surveillance are needed to prevent rupture and ensure timely repair for patients with AAA.