Although venous thromboembolic events are relatively rare in children, they are an increasingly recognized clinical entity in pediatric tertiary care hospitals. Although vascular disorders are prevalent with Down syndrome, it remains unclear whether Down syndrome patients are at higher risk for venous thromboembolic events. We report two adolescent cases with Down syndrome who unexpectedly developed venous thromboembolism in a general care unit. Our cases had a few risk factors; laparoscopic radical surgery for Hirschsprung's disease with central venous catheterisation in Case 1, and bacterial hepatic abscess in Case 2. Despite preventive heparinization with catheterisation and minor surgery in Case 1 and non-sepsis in Case 2, bed rest for only a few days triggered sudden onset of deep vein thrombosis in lower limbs with pulmonary thromboembolism in both cases. We speculate that the characteristics of Down syndrome, including physical and behavioural problems, might cause venous thromboembolic events. Thus, we should pay more attention to the relationship specifically between venous thromboembolism and Down syndrome, especially in adolescents, and increase prevention, early detection and treatment efforts.

Keywords: Down syndrome, adolescent, immobility, venous thromboembolism