Total knee arthroplasty (TKA) is one of the most successful procedures in orthopaedic surgery. Nevertheless, significant postoperative blood loss and requirement of blood transfusion are still problematic. Total blood loss in TKA can be divided into visible and invisible blood loss. Visible blood loss (VBL) means blood loss from the surgical field and wound drainage while invisible blood loss (IBL) means residual blood in the knee, extravasation into the tissues and loss due to haemolysis.