When a serum separation tube (SST) is collected, which of the following actions should the phlebotomist take to ensure optimal test results?
Invert the tube 5 to 8 times and then set for 30 minutes prior to centrifugation.
Invert the tube 1 to 3 times and then set for 1 hour prior to centrifugation.
Invert the tube 2 to 4 times and then set for 15 minutes prior to centrifugation.
Invert the tube 8 to 10 times and then set for 2 hours prior to centrifugation.
The Correct Answer is A
Choice A reason:
Inverting the tube 5 to 8 times ensures that the clot activator mixes thoroughly with the blood, promoting proper clotting. Setting the tube aside for 30 minutes allows sufficient time for the blood to clot before centrifugation. This is the recommended procedure to ensure that the serum is properly separated from the clot, resulting in a quality specimen suitable for testing.
Choice B reason:
Inverting the tube only 1 to 3 times may not be enough to mix the clot activator with the blood adequately, which could lead to incomplete clotting and potentially compromised test results. Additionally, setting the tube for 1 hour before centrifugation is longer than necessary and does not offer any advantage over the recommended 30 minutes.
Choice C reason:
Inverting the tube 2 to 4 times might not fully mix the clot activator with the blood, and setting it for only 15 minutes does not provide enough time for proper clot formation. This could result in a suboptimal separation of serum and clot, affecting the integrity of the test results.
Choice D reason:
Inverting the tube 8 to 10 times could potentially cause hemolysis or disruption of the blood cells due to excessive agitation. Setting the tube for 2 hours prior to centrifugation is not recommended as it could lead to serum degradation or other changes that may affect the test results.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A reason:
Having the bevel down at a 30° angle is not the correct needle position for venipuncture. The bevel of the needle should be facing up to allow for a smoother insertion and to minimize the risk of damaging the vein or causing discomfort to the patient.
Choice B reason:
Positioning the bevel up at a 45° angle is not recommended for venipuncture as this angle is too steep and could lead to the needle penetrating through the vein, potentially causing a hematoma or other complications.
Choice C reason:
The bevel up at a 30° angle is the correct position for venipuncture. This position allows the phlebotomist to insert the needle with the bevel facing upwards, which is the sharpest part of the needle, ensuring a clean entry into the vein. The 30° angle is shallow enough to enter the vein without going through it and causing injury.
Choice D reason:
A bevel down at a 45° angle is incorrect for the same reasons as choice B. Additionally, with the bevel down, the non-beveled side, which is duller, would make the initial contact with the skin, potentially causing more pain and making it more difficult to penetrate the vein.
Correct Answer is D
Explanation
Choice A reason:
Heparin is an anticoagulant, not a clot activator. It works by inhibiting thrombin and preventing the conversion of fibrinogen to fibrin, thus preventing clot formation. It is commonly found in green-top tubes and is suitable for collecting plasma samples for tests like electrolyte levels and coagulation studies.
Choice B reason:
Oxalate is also an anticoagulant that prevents clotting by precipitating calcium. It is not used to promote clot formation but rather to maintain a blood sample in a non-coagulated state for various tests.
Choice C reason:
Citrate functions similarly to heparin and oxalate as an anticoagulant. It chelates calcium ions in the blood, inhibiting the coagulation process. Citrate is often used in blue-top tubes and is ideal for collecting plasma samples for coagulation studies.
Choice D reason:
Silica is a clot activator. It is commonly used in serum separator tubes (SSTs) with a gold or red speckled top. The silica particles provide a surface for the rapid formation of the clot, allowing for the separation of serum from the blood cells. This is essential when serum is needed for testing.
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