Final answer:
The phlebotomist must centrifuge a serum specimen to separate cells from the serum, ensuring the sample is clear and uncontaminated for accurate diagnostic testing at an outside lab. the correct option is a) cells must be separated from the serum .
Step-by-step explanation:
A phlebotomist must centrifuge a serum specimen before shipment to an outside reference lab because cells must be separated from the serum.
When a blood sample is centrifuged, it separates into three layers based on density: the top layer is the plasma, the middle layer is the buffy coat containing white blood cells (leukocytes) and platelets (thrombocytes), and the bottom layer is composed of red blood cells (erythrocytes).
The centrifugation ensures that the cellular components are compacted at the bottom, allowing the clear serum, which does not contain the blood clotting factors present in plasma, to be collected for analysis.
This process is critical for accurate diagnostic testing, as the presence of cells could interfere with the results. Separation by centrifugation also prevents the cells from hemolyzing, which could release intracellular contents and further contaminate the serum.