Universal precautions apply to all specimens of blood, serum, plasma, blood products, vaginal secretions, semen, cerebro-spinal fluid, synovial fluid, pleural fluid, peritoneal fluid, pericardial fluid, amniotic fluid, and concentrated HIV or HBV viruses. Any specimen of any type which contains visible traces of blood should be handled using Universal Precautions.
Serum is the intracellular fluid in blood without the clotting factors. Serum is the specimen of choice for many tests because clotting factors can interfere with certain chemistry procedures.
Serum is obtained by centrifuging clotted blood. This means that whole blood specimens must be allowed to fully clot before the centrifugation process or a fibrin clot will form in the serum, resulting in a loss of total serum volume.
Serum should be separated from the red cells by either a gel barrier or by pipetting off the serum into a separate tube.
Plasma is the intracellular fluid in blood containing inactivated clotting factors. Plasma is prepared by centrifuging anti-coagulated whole blood from either an EDTA tube or a heparin tube. The centrifugation process can take place immediately, thus making plasma ideal for STAT procedures, when available/possible.