Which of the following is the correct order of collection?
Citrate, heparin, EDTA, fluoride
Citrate, EDTA, heparin, fluoride
Fluoride, EDTA, heparin, citrate
Fluoride, heparin, EDTA, citrate
The Correct Answer is B
Choice A reason:
The order of citrate, heparin, EDTA, and fluoride is not the correct sequence for blood collection. The correct order is essential to prevent cross-contamination of additives between tubes, which could interfere with test results. Citrate tubes should be drawn first to ensure that the blood does not clot prematurely, but heparin should not follow immediately after citrate.
Choice B reason:
Citrate tubes, which contain sodium citrate, are used for coagulation tests and must be drawn first to ensure the proper blood-to-additive ratio. EDTA tubes are drawn next because EDTA binds calcium and prevents clotting, making it ideal for complete blood counts and other hematology studies. Heparin tubes, which prevent clotting by inhibiting thrombin and thromboplastin, are drawn after EDTA. Lastly, fluoride tubes, which contain a glycolysis inhibitor, are drawn to preserve glucose levels and are typically used for glucose and lactate testing.
Choice C reason:
Starting with fluoride is not recommended as it could lead to contamination of the EDTA and heparin tubes with fluoride, which could affect the results of certain tests, such as calcium determinations in heparin tubes. The order of draw is designed to minimize such risks.
Choice D reason:
This sequence is incorrect because fluoride tubes are not drawn before EDTA and heparin tubes. The presence of fluoride could potentially contaminate the subsequent tubes and alter the results of the tests that require heparin or EDTA as an anticoagulant.
In phlebotomy, following the correct order of draw is crucial. The order is established based on the type of additive in each tube and its potential to interfere with tests conducted in subsequent tubes. The standard order is: blood cultures, citrate tubes, serum tubes with or without clot activator and gel, heparin tubes with or without gel, EDTA tubes, and lastly, fluoride tubes. This sequence helps prevent cross-contamination and ensures the accuracy of laboratory results, which are critical for patient diagnosis and treatment.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A Reason:
A glucose tolerance test is used to diagnose diabetes by measuring the body's response to glucose over a period of time. It is not used to identify bacteremia, which is the presence of bacteria in the bloodstream.
Choice B Reason:
A peripheral blood smear involves examining a sample of blood under a microscope to look for abnormalities in blood cells. While it can reveal signs of infection, it does not specifically identify bacteremia.
Choice C Reason:
A blood culture is the primary test used to detect bacteremia. It involves taking a sample of blood and incubating it to see if bacteria grow, which would indicate the presence of bacteria in the bloodstream.
Choice D Reason:
Lactic acid levels in the blood are measured to assess the severity of sepsis, a condition that can result from bacteremia. Elevated lactic acid can indicate that tissues are not getting enough oxygen, but the test itself does not identify bacteremia.
Correct Answer is B
Explanation
Choice A reason:
The BUN test measures the amount of urea nitrogen in the blood, which can indicate kidney function. Fasting is not typically required for a BUN test unless it is being conducted alongside other tests that may require fasting.
Choice B reason:
An HDL test is part of a lipid profile that measures the levels of good cholesterol in the blood. Fasting before a cholesterol test, including HDL, is often recommended to ensure accuracy, although recent guidelines have changed, allowing for nonfasting cholesterol testing in certain individuals.
Choice C reason:
An ABG test measures oxygen and carbon dioxide levels in the blood and assesses the body's acid-base balance. Preparation for an ABG test does not typically require fasting, but patients may need to stop supplemental oxygen before the test to get accurate measurements.
Choice D reason:
A CBC test, or complete blood count, does not require fasting. It measures various factors of the blood, including red and white blood cells and platelets. Fasting is not necessary unless the CBC is part of a panel of tests that includes tests requiring fasting.
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