Final answer:
A light blue top tube containing sodium citrate as an anticoagulant is delivered to the coagulation department for testing. Within a glass tube, the blood clots and separates, allowing the serum to be harvested for analysis after about an hour.
Step-by-step explanation:
A light blue top tube in a laboratory setting typically contains sodium citrate as an anticoagulant and is most commonly used for coagulation testing. Upon receiving a light blue top tube, a lab technician would deliver it to the coagulation department of the laboratory for analysis. Coagulation tests commonly performed on plasma from blood collected in light blue top tubes include prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen level determination. During the processing of the blood sample within the glass tube, which may refer to the process mentioned in the question, the blood clots and the cellular components settle at the bottom due to gravity. The liquid portion of the blood that remains after the clot has formed is the serum. This is why, after about an hour, the lab technician can harvest serum for further blood analysis, as the clotting process would have occurred during this time, separating the serum from the clotted cells.