Do asymptomatic clots in children matter?

Asymptomatic venous thrombosis is a common complication among hospitalised paediatric patients. Previous guidelines recommend the treatment of all asymptomatic venous thrombosis, even when the diagnosis is made incidentally or the risk factor is no longer present. Whether clinicians need to treat all asymptomatic thrombosis in children, given the likelihood of long-term sequelae, is unclear and there are significant risks associated with anticoagulation treatment. Asymptomatic thrombosis in children is most frequently associated with central venous catheters (CVCs). The incidence of asymptomatic CVC-related VTE is highest in cohorts of children with cancer, but also reported in neonates, children with congenital heart disease and critically ill children. There is significant variation in reported rates of CVC-related thrombosis among cohorts of children with different underlying diseases and of various ages. As asymptomatic thrombosis is often an incidental finding, rates of asymptomatic VTE in children are most likely underestimated. Evidence about the incidence, characteristics and long-term outcomes associated with asymptomatic thrombosis in children often lacks precision as data is presented collectively with symptomatic thrombosis. This review discusses the current evidence pertaining to the necessity for screening for asymptomatic thrombosis, the risk benefit ratio of treatment and the risk of long-term morbidity. To confidently determine the clinical significance of asymptomatic VTE in children, prospective studies with extended follow up are needed.