ASCP Phlebotomy — Questions and Answers
Question 1: What shade of tube should be used when taking a sample to check blood alcohol levels?
- Gray. (Correct answer)
- Yellow.
- Red.
- Royal Blue.
Correct answer: Gray.
Gray-top tubes are used for blood alcohol levels because they contain sodium fluoride, which acts as an antiglycolytic agent. Sodium fluoride prevents glucose metabolism by red blood cells, ensuring that the alcohol concentration remains stable and accurate over time. These tubes also typically contain potassium oxalate as an anticoagulant.
Question 2: What should be added to a sample if it needs to be diluted?
- Preservative.
- Diluent. (Correct answer)
- Anticoagulant.
- All of the above.
Correct answer: Diluent.
A diluent is a substance, typically a liquid, used to reduce the concentration of a solution or suspension. When a blood sample needs to be diluted for specific laboratory tests, a precise amount of diluent is added to achieve the correct concentration for accurate analysis. Preservatives and anticoagulants serve different functions related to sample integrity.
Question 3: What component of blood is potassium EDTA able to bind to?
- Magnesium.
- Iron.
- Calcium. (Correct answer)
- All of the above.
Correct answer: Calcium.
Potassium EDTA (Ethylenediaminetetraacetic acid) acts as an anticoagulant by binding to calcium ions in the blood. Calcium is a crucial cofactor required for the coagulation cascade, and by chelating (binding) free calcium, EDTA effectively prevents the blood from clotting. This makes EDTA tubes suitable for hematology tests where whole blood is needed.
Question 4: Which of the following can affect a blood sample if the patient refuses to fast when instructed to do so?
- Increasing stress hormones.
- Increasing enzymes such as creatinine and fatty acids.
- A false increase in analytes.
- Increasing its turbidity. (Correct answer)
Correct answer: Increasing its turbidity.
If a patient fails to fast as instructed before a blood draw, the presence of recently ingested fats (lipids) in the bloodstream can cause the serum or plasma to appear cloudy or milky. This condition is known as lipemia, and the increased turbidity can interfere with various laboratory tests, leading to inaccurate or falsely elevated results for certain analytes.
Question 5: What should you do if you realize that a patient's name is spelled differently on the requisition and the patient's armband?
- Visit with your manager to verify the information and have it corrected. (Correct answer)
- Ask the patient to go get the requisition corrected.
- Assume there was a typo and ignore the requisition.
- Any of the above.
Correct answer: Visit with your manager to verify the information and have it corrected.
Patient identification is paramount in healthcare. If there is any discrepancy between a patient's name on the requisition and their armband, the phlebotomist must not proceed with the draw. The correct action is to immediately report the discrepancy to a manager or nursing staff to verify the patient's identity and have the information corrected, preventing potential medical errors.
Question 6: Which of the following actions is required to correctly anchor a vein?
- Increasing pressure on the tip of the needle.
- Placing your thumb to the side of the vein and pressing firmly.
- Placing the thumb of your free hand below the vein and stretching the skin. (Correct answer)
- All of the above.
Correct answer: Placing the thumb of your free hand below the vein and stretching the skin.
To correctly anchor a vein, the phlebotomist should place the thumb of their free hand approximately 1-2 inches below the intended venipuncture site. By stretching the skin downwards, the vein is stabilized and prevented from rolling, which facilitates a smoother and more successful needle insertion. This technique minimizes patient discomfort and reduces the risk of missing the vein.
Question 7: Which of the following is the most typical reason for blood culture contamination?
- Improper storage.
- Improper site preparation. (Correct answer)
- Improper transportation.
- All of the above.
Correct answer: Improper site preparation.
Improper site preparation is the most common reason for blood culture contamination. If the venipuncture site is not meticulously cleaned and disinfected according to protocol, bacteria from the patient's skin can be introduced into the blood culture bottles. This leads to false-positive results, potentially causing unnecessary antibiotic treatment and delaying proper diagnosis.
ASCP Phlebotomy
What shade of tube should be used when taking a sample to check blood alcohol levels?