59. When a serum separation tube (SST) is collected, which of the following actions should the phlebotomist take to ensure optimal test results?
Answer: A
Invert the tube 5 to 8 × and then set for 30 min prior to centrifugation.
To ensure optimal test results when collecting a serum separation tube (SST), the phlebotomist should invert the tube 5 to 8 times and then allow it to stand for 30 minutes before centrifugation.
A) Invert the tube 5 to 8 × and then set for 30 min prior to centrifugation.
This option is correct because inverting the SST 5 to 8 times helps to mix the blood with the clot activator, ensuring proper clot formation. Allowing the tube to set for 30 minutes before centrifugation is also recommended to facilitate the separation of serum from the clot efficiently.
B) Invert the tube 1 to 3 × and then set for 1 hr prior to centrifugation.
This option is incorrect as inverting the tube only 1 to 3 times does not adequately mix the blood with the clot activator, which can lead to incomplete clotting. Additionally, waiting for 1 hour is longer than the recommended time, which could compromise test results.
C) Invert the tube 2 to 4 × and then set for 15 min prior to centrifugation.
This option is incorrect because inverting the tube only 2 to 4 times may not ensure sufficient mixing of the blood with the clot activator. Furthermore, a standing time of 15 minutes is shorter than the recommended 30 minutes, which may result in suboptimal serum separation.
D) Invert the tube 8 to 10 × and then set for 2 hr prior to centrifugation.
This option is incorrect as inverting the tube 8 to 10 times may be excessive and can potentially cause hemolysis. Additionally, a 2-hour waiting period is unnecessarily long and can lead to deterioration of the sample quality, affecting test results.
Conclusion
The correct procedure for collecting and preparing a serum separation tube involves inverting it 5 to 8 times followed by a 30-minute wait before centrifugation. Other options either fail to provide adequate mixing or involve inappropriate waiting times, which can negatively impact the quality and reliability of the test results. Hence, option A is the only choice that meets the established guidelines for optimal SST processing.