Which of the following methods should a phlebotomist use to invert tubes to prevent clotting?

Choice A Reason:
Withdrawing the needle completely would be an incorrect action because it would end the procedure prematurely and require a new venipuncture, causing unnecessary discomfort to the patient. It should only be done if the venipuncture has been completed or if there is a need to stop due to a complication.

Choice B Reason:
Rotating the bevel of the needle could potentially reposition the needle for better blood flow if it has become occluded or is not properly aligned with the vein. However, this action should be done with caution to avoid causing injury to the vein or discomfort to the patient.

Choice C Reason:
Increasing tourniquet pressure is not advisable once blood flow has been established, as it could cause damage to the vein or hemolysis of the blood sample. The tourniquet should be released once the blood starts flowing into the first tube to avoid these issues.

Choice D Reason:
Activating a new evacuated tube is the correct action to take when blood flow stops upon attaching a second tube. This could indicate a problem with the vacuum in the tube rather than with the needle or the venipuncture site. Trying a new tube can resolve the issue without needing to adjust the needle or the patient's position.

Choice A reason:
The light green tube typically contains lithium heparin and is used for plasma determinations in chemistry. It is not suitable for coagulation studies, such as PT, because heparin is an anticoagulant that would interfere with the test results.

Choice B reason:
The lavender tube contains EDTA, which is an anticoagulant that binds calcium. While it is commonly used for complete blood counts (CBC) and other hematology tests, it is not appropriate for coagulation studies because the binding of calcium would affect the clotting process required for a PT test.

Choice C reason:
The royal blue tube can come with different additives or be additive-free, depending on the color of the closure. It is primarily used for trace element testing, toxicology, and nutrient determinations. The additives in a royal blue tube could potentially contaminate the sample and interfere with the PT test.

Choice D reason:
The light blue tube contains sodium citrate, which is the appropriate anticoagulant for coagulation studies like PT. Sodium citrate works by binding calcium in the blood, preventing clotting. The PT test measures the time it takes for a clot to form after re-calcification, making the light blue tube the correct choice for this test.