Final answer:
The yellow top tube should come first in the order of draw to avoid contamination of the blood sample. This step is essential in preserving the integrity of blood cultures and other tests.
Step-by-step explanation:
The question pertains to phlebotomy, specifically the order of draw during blood sample collection. The order of draw is crucial to prevent cross-contamination and ensure accurate test results. When following the order, the tube that should always come first is the yellow top tube (D), which contains the additive sodium polyanetholesulfonate (SPS) and is typically used for blood culture specimen collections.
This tube precedes others because it is critical to avoid contamination of the sterile blood culture with additives from other tubes. However, sometimes the order can vary depending on the specific additives and tests required, but generally, the blood culture tubes, including the yellow top, precede all other tubes.