A phlebotomist needs to collect a PT (Prothrombin Time) from a patient with a difficult vein. Which of the following is the best tube for the draw?
Light green
Lavender
Royal blue
Light blue
The Correct Answer is D
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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A reason:
A sodium level test is important for managing and monitoring a patient's electrolyte balance, particularly in critical care settings. However, a DNR order indicates that the patient has chosen not to undergo CPR, not necessarily that their condition is the most critical at the moment. Therefore, while important, it may not be the most urgent sample to process.
Choice B reason:
Postoperative monitoring of hemoglobin and hematocrit levels is crucial for detecting possible hemorrhage and ensuring proper recovery. However, unless there is an immediate concern for acute blood loss or other complications, these tests may not be as urgent as a stat test from the emergency room.
Choice C reason:
A stat potassium level is typically ordered when there is an urgent need to assess a patient's potassium due to conditions that can rapidly affect heart rhythm and muscle function. In the emergency room setting, where patients often present with acute and life-threatening conditions, stat tests are prioritized to provide rapid results that can influence immediate clinical decisions.
Choice D reason:
Peak antibiotic levels are measured to ensure therapeutic efficacy and to avoid toxicity. While important for managing a patient's treatment, especially for those who are NPO (nothing by mouth), it may not be as time-sensitive as a stat test required for an acute emergency.
Correct Answer is C
Explanation
Choice A Reason:
Povidone-iodine is an antiseptic used for skin disinfection before and after surgery. It has a broad spectrum of antimicrobial activity, but it is not the preferred choice for capillary blood collection due to the potential interference with certain laboratory tests. Povidone-iodine needs to be completely dried to avoid hemolysis of the sample, which can affect test results.
Choice B Reason:
Hand sanitizer is generally used for hand hygiene and not for the disinfection of the site for blood specimen collection. While it is effective in killing germs on the skin, it contains emollients and gelling agents that can contaminate the blood sample and interfere with laboratory tests.
Choice C Reason:
70% isopropyl alcohol is the most commonly used disinfectant for aseptic technique in capillary blood collection. It is effective against a broad range of microorganisms and evaporates quickly, leaving no residue that could contaminate the sample. It is important to allow the alcohol to dry completely before performing the puncture to prevent stinging and sample dilution.
Choice D Reason:
A 10% chlorine bleach solution is not typically used for skin disinfection in blood collection due to its harshness and potential to cause skin irritation and damage. It is more commonly used for disinfecting surfaces and equipment in healthcare settings.
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