['Excessive bleeding can be a problem during or after cardiac surgery. While cardiopulmonary bypass-associated platelet dysfunction is an important inducer of coagulopathy, preoperative platelet dysfunction can also contribute to this bleeding. We investigated the relationship between preoperative platelet dysfunction and transfusion of blood products given to children undergoing cardiac surgery.', 'The platelet function analyser test measures platelet function in vitro by aspirating blood through a small standard hole (creating high shear) in a collagen membrane infused with a platelet agonist. The time taken to form a platelet plug is known as closure time and prolonged closure time (CT) indicates platelet dysfunction. Three hundred and thirty-eight children who had undergone surgery with cardiopulmonary bypass between 2008 and 2012 were included. The volume of red blood cells and fresh-frozen plasma transfused was recorded. The relationship between closure time and transfusion requirements was analysed using linear and logistic regression.', 'Patients with prolonged closure time had greater odds of getting red blood cells and fresh-frozen plasma transfusions compared with patients with normal closure time (P <0.01). On univariate analysis, age, weight, haematocrit, cardiopulmonary bypass time, Risk Adjustment for Congenital Heart Surgery score and closure time were associated with increased odds of red blood cells and fresh-frozen plasma transfusion in the operation theatre (P <0.05). However, when logistic multivariable regression analysis was applied, only age, cardiopulmonary bypass time and closure time remained as significant predictive factors for transfusion.'] Does preoperative platelet dysfunction predict blood product transfusion in children undergoing cardiac surgery?