Evidence review: periprocedural use of blood products.

Blood product transfusion has not been subject to rigorous clinical study, and great practice variations exist. Of particular concern to hospitalists is the use of red blood cells, plasma, and platelets prior to invasive procedures to correct anemia or perceived bleeding risk. We summarize the known risks associated with periprocedural anemia, prolonged international normalized ratio (INR), and thrombocytopenia, as well as the effects of blood product administration on clinical outcomes. Clinical trial evidence argues for a restrictive red blood cell transfusion threshold (a hemoglobin level of 7-8 g/dL or symptomatic anemia) for most perioperative patients. There are no high-quality data to guide plasma and platelet transfusions around the time of procedures. Available data do not support the use of prothrombin time/INR to guide prophylactic administration of plasma, and there are scarce data to guide platelet use around the time of an invasive procedure. Therefore, we rely on current consensus expert opinion, which recommends administration of plasma in moderate- to high-risk procedures when INR is >1.5. We recommend platelet transfusion in low-risk procedures when platelet count is <20,000/μL, for average-risk procedures when platelet count is <50,000/μL, and for procedures involving the central nervous system when the platelet count is <100,000/μL.