Final answer:
Green (PST) tubes do not need to be inverted because they contain a gel that separates the plasma from the cells.
Step-by-step explanation:
When using green (PST) tubes, there is no need to invert them.
Green (PST) tubes are used for the collection of plasma in blood tests. Inverting tubes is necessary for tubes containing anticoagulants, such as purple (EDTA) or blue (sodium citrate) tubes, to prevent clotting. However, green (PST) tubes contain a gel that separates the plasma from the cells, eliminating the need for inversion.