Final answer:
Inverting laboratory tubes after phlebotomy ensures proper mixing of blood with any additives to prevent clotting and ensure accurate testing. It allows the serum to be harvested for analysis after the blood separates over time or after centrifugation.
Step-by-step explanation:
After performing phlebotomy, inverting laboratory tubes is an essential step to ensure that any additives present in the tubes, like anticoagulants (K2EDTA, lithium heparin) or stabilizers, are thoroughly mixed with the blood. This process prevents clotting and ensures accurate results during blood analysis. When a phlebotomist collects a blood sample in a glass tube and leaves it to rest for about an hour, the blood begins to clot, and the cellular components, such as red and white blood cells, start to separate from the serum due to gravity. If the tube contains an anticoagulant, the blood will not clot but will instead separate into plasma and cellular components when centrifuged. The serum or plasma can then be harvested for further medical analysis or for various testing procedures.