Paediatric blood transfusion. Nurse adjusting the settings on an intravenous drip containing donated blood. The drip is connected to a catheter that has been inserted in the child's wrist vein (centre right) and blood is being added to their bloodstream. Blood transfusions are carried out to replace blood in patients with blood disorders, such as thalassaemia, anaemia and haemophilia. They are also needed by people who have lost blood through trauma or surgery. The blood group and type of the donated blood needs to match that of the patient in order to prevent rejection of the blood.