How is the order of draw determined?

The order of draw is determined based on laboratory requirements to ensure accurate test results when multiple blood specimens are collected during a single venipuncture. This sequence is crucial because it minimizes the risk of cross-contamination between different additives in the collection tubes, which can interfere with laboratory tests. Each type of collection tube contains specific additives that can react with each other if drawn out of order, potentially compromising the integrity of the samples collected.

For instance, if a tube with an anticoagulant is drawn before a serum tube, the anticoagulant could contaminate the serum sample and lead to erroneous test outcomes. Thus, laboratory protocols mandate a specific order that generally starts with blood culture tubes, followed by citrate tubes, and continues through other tube types based on their additives. Adhering to these guidelines is essential for the reliability of laboratory results. The other options do not follow the established standards required for maintaining sample integrity.