Venous Thromboembolism in Children

Case 1: A 4-year-old boy with acute lymphoblastic leukemia (ALL) and disseminated candidiasis was found to have a right atrial thrombus on a routine imaging study. He had a central venous catheter (CVC) and was receiving chemotherapy that contained asparaginase. Thrombophilia workup was negative.Case 2: A 17-year-old girl presented to the emergency department with a 3-week history of left-sided chest pain and shortness of breath. She had been taking high-dose estrogen therapy for congenital tall stature. D-dimer was positive. Chest CT revealed multiple small pulmonary emboli and infarcts. Lower-extremity venous ultrasound was negative for deep vein thrombosis, and echocardiography showed normal right ventricular function. Thrombophilia workup was negative.Decreased capacity to generate thrombin, increased capacity of α2-macroglobulin to inhibit thrombin, and enhanced antithrombotic potential by the vessel wall appear to contribute to the low incidence of venous thromboembolism (VTE) during childhood. Nevertheless, VTE is being diagnosed more frequently in children. The annual incidence is 0.07 to 0.14 per 10 000 children, or 5.3 per 10 000 hospital admissions of children, and 24 per 10 000 admissions to neonatal intensive care units.1–3 The highest incidence is during the neonatal period, followed by another peak in adolescence. Patients in neonatal and pediatric intensive care units and oncology patients are particularly at high risk. Teenage girls have twice the rate of VTE as do teenage boys. This appears to be due to the use of oral contraceptives and pregnancy.4 Risk FactorsIdiopathic VTE in the pediatric population is relatively infrequent and is almost always associated with an underlying disease or risk factor. Both congenital and acquired conditions contribute to the development of thrombosis. More than 90% of children with VTE will have ≥2 predisposing factors (Figure). Figure 1. Risk factors for childhood VTE. Acquired Conditions The presence of a CVC is the …