OBJECTIVE. Diastolic runoff in the abdominal aorta, with subsequent circulatory mesenteric insufficiency, has been postulated as a cause of necrotizing enterocolitis in term infants with congenital heart disease. With this study we sought to determine whether Doppler-flow characteristics in the abdominal aorta can predict which infants are at specific risk, independent of gestational age and type of congenital heart disease. PATIENTS AND METHODS. We conducted a case-control study of term infants with congenital heart disease and proven necrotizing enterocolitis (n = 18) compared with gestational age-matched and diagnosis-matched control subjects (n = 20). Abdominal aortic Doppler velocities, time intervals, and reversals were analyzed. Groups were compared, and independent risk factors for necrotizing enterocolitis were determined. RESULTS. The groups were similar with regard to weight, pulse pressure, use of prostaglandins or inotropes, presence of a patent ductus arteriosus, and systolic function. However, 47% of the case subjects with necrotizing enterocolitis had persistent retrograde diastolic flow in the abdominal aorta compared with 15% of the control subjects. When adjusting for multiple risk factors, persistent diastolic flow reversal remained the only factor significantly associated with necrotizing enterocolitis. CONCLUSION. Persistent diastolic flow reversal in the abdominal aortic Doppler profile is associated with an increased risk of necrotizing enterocolitis in term infants with congenital heart disease irrespective of gestational age or anatomic type of congenital heart disease. Copyright © 2007 by the American Academy of Pediatrics.