Which one of the following tubes is filled first when multiple tubes are filled using an evacuated tube system?

In an evacuated tube system, blood culture tubes, specifically those containing sodium polyanethol sulfonate (SPS), should be filled first when collecting blood samples. This is primarily because blood cultures are critical for detecting infections in the bloodstream, and any contamination from subsequent tubes could lead to false positives. Filling the blood culture tubes first minimizes the risk of contamination with additives present in other tubes, such as anticoagulants and gels, which could hinder the growth of microorganisms.

Following the blood culture tubes, the typical order of draw suggests that citrate tubes should be filled next, as they are used for coagulation studies and could be affected by the presence of additives from the prior tubes if they are filled out of turn.

Understanding the proper order of tube filling is essential to ensure accurate test results and reliable diagnosis, reinforcing the importance of adhering to established protocols during blood collection.