NCCT Phlebotomy Technician (NCPT) Practice Exam

The correct answer is the coagulation tube (blue) because, according to the CLSI (Clinical and Laboratory Standards Institute) recommended order of draw, it follows the collection of blood culture tubes. Blood culture tubes are typically drawn first to prevent contamination that could affect the results of cultures. After blood cultures, the next tube to be drawn is the coagulation tube, which contains additives like sodium citrate that are crucial for proper coagulation testing.

By placing the coagulation tube second, it ensures that potential contaminants from other tube additives are minimized, which is essential for accurate laboratory results. Serum tubes, glycolytic inhibitor tubes, and other types of tubes follow in the order of draw. The primary goal is to maintain the integrity of each sample type and reduce the risk of cross-contamination between different additives, thereby ensuring reliable test outcomes.