What is the correct order of draw for the evacuated tube system?

The correct order of draw for the evacuated tube system is critical for ensuring accurate laboratory results by preventing cross-contamination of additives from one tube to another. This process is based on the tube contents, particularly whether they contain additives like anti-coagulants, separators, or other preservatives.

Starting with blood culture tubes is crucial since these tubes are used to detect the presence of microorganisms and require a sterile environment. Collecting blood culture first minimizes the risk of contamination from the skin flora, which could affect the results.

Next in the sequence is coagulation tubes. These tubes contain an anticoagulant, typically sodium citrate, and are designed for tests such as prothrombin time (PT) and activated partial thromboplastin time (aPTT). Drawing these tubes after blood cultures helps ensure that any additives from subsequent tubes do not interfere with coagulation tests.

Following coagulation tubes, nonadditive tubes are drawn. These are plain tubes without additives, often used for serological tests. The rationale for placing these after coagulation is to maintain the integrity of coagulation factors that could be affected by other substances.

Finally, gel separator or other additive tubes are collected. These tubes typically contain a gel that separates serum or plasma from the cellular components upon centrif