Participants	People of all ages with a low platelet count who are due to have surgery
Experimental intervention 1	Prophylactic platelet transfusion before surgery
Control intervention 1	No Prophylactic platelet transfusion before surgery
Control intervention 2	Artificial platelet substitutes for example lyophilised platelets, infusible plasma membranes and liposomes with inserted platelet receptors
Control intervention 3	Cryosupernatant
Control intervention 4	Thrombopoietin (TPO) mimetics
Control intervention 5	Antifibrinolytic drugs
Outcomes	Primary outcomes Mortality (all‐causes, secondary to bleeding, secondary to thromboembolism and secondary to infection) within 30 days and 90 days of surgery. The number of participants with major procedure‐related bleeding within 7 days of surgery, defined as: Surgical site bleeding requiring a second intervention or reoperation or surgical site bleeding that causes a haematoma or haemarthrosis of sufficient size to delay mobilisation or wound healing, Bleeding of sufficient size to cause delayed wound healing, or wound infection or surgical site bleeding that is unexpected and prolonged or causes haemodynamic instability (as defined by the study) that is associated with a 20g/L drop in Hb Bleeding that requires two or more units of whole blood/red cells within 24h of the bleeding Bleeding that defined by the study with no further details Secondary outcomes The number of participants with minor procedure‐related bleeding within 7 days of surgery (e.g. haematoma, prolonged bleeding at surgical site that does not fulfil the definition for major bleeding) Number of platelet transfusions per participant and number of platelet components per participant Number of red cell transfusions per participant and number of red cell components per participant Proportion of participants requiring additional interventions to stop bleeding (surgical, medical e.g. tranexamic acid, other blood products e.g. fresh frozen plasma (FFP), cryoprecipitate, fibrinogen) within 7 days from the surgery Quality of life assessment using validated tools Serious adverse events due to:Transfusion (transfusion reactions, transfusion‐related acute lung injury (TRALI), transfusion related infection, transfusion‐associated circulatory overload (TACO), transfusion‐related dyspnoea) within 24 hours of the transfusion Surgery (e.g. delayed wound healing, infection) within 30 days after the operation;Length of hospital stay and length of ITU stay Venous and arterial thromboembolism (including deep vein thrombosis; pulmonary embolism; stroke; myocardial infarction)