ASCP Phlebotomy 3 — Questions and Answers
Question 1: Which vein is the most commonly used site for routine venipuncture in adults?
- Cephalic vein
- Median cubital vein (Correct answer)
- Basilic vein
- Dorsal hand vein
Correct answer: Median cubital vein
The median cubital vein is the preferred site for routine venipuncture because it is large, well-anchored, close to the surface, and less painful than other sites.
The median cubital vein is located in the antecubital fossa (the bend of the elbow) and is the most commonly selected site for routine venipuncture. It is preferred because it is typically large and well-anchored by surrounding tissue, making it less likely to roll during needle insertion. It is also close to the skin surface and located away from major nerves and arteries.
Question 2: A patient has an IV running in the left arm. What is the correct phlebotomy procedure?
- Draw from the left arm below the IV site
- Draw from the right arm (Correct answer)
- Turn off the IV for 2 minutes and then draw from the left arm
- Draw from the left arm above the IV site
Correct answer: Draw from the right arm
When a patient has an IV in one arm, the preferred approach is to draw blood from the opposite (contralateral) arm to avoid contamination from IV fluids.
Drawing blood from an arm with an active IV infusion can contaminate the specimen with IV fluids, leading to diluted or inaccurate results. The standard practice is to draw from the opposite arm. If both arms have IVs, consult the nurse about turning off the IV for at least 2 minutes and discarding the first 5 mL before collecting. Drawing below the IV site is never acceptable as fluid flows downward through veins.
Question 3: What is the maximum time a tourniquet should remain on a patient's arm during venipuncture?
- 30 seconds
- 1 minute (Correct answer)
- 3 minutes
- 5 minutes
Correct answer: 1 minute
A tourniquet should not remain applied for more than 1 minute to prevent hemoconcentration and erroneous test results.
CLSI guidelines recommend that a tourniquet should not be applied for more than one minute. Prolonged tourniquet application causes hemoconcentration, artificially increasing the concentration of larger molecules such as proteins, lipids, and cell counts. If the tourniquet must be reapplied, wait two minutes to allow blood flow to normalize.
Question 4: Which antiseptic is required for blood culture collection site preparation?
- 70% isopropyl alcohol only
- Povidone-iodine or chlorhexidine (Correct answer)
- Hydrogen peroxide
- Soap and water
Correct answer: Povidone-iodine or chlorhexidine
Blood culture site preparation requires povidone-iodine or chlorhexidine gluconate because these antiseptics provide more thorough skin disinfection than alcohol alone.
Blood cultures require meticulous skin preparation to prevent false-positive results from skin flora contamination. The standard protocol uses either 1-2% chlorhexidine gluconate with alcohol or povidone-iodine (Betadine). The site is first cleaned with 70% isopropyl alcohol, then the antiseptic is applied in concentric circles from the center outward. The antiseptic must be allowed to dry completely before venipuncture.
Question 5: Which of the following conditions would make a site unacceptable for venipuncture?
- The patient has a tattoo on their forearm
- The arm is on the same side as a mastectomy (Correct answer)
- The patient reports mild anxiety about needles
- The patient is wearing long sleeves
Correct answer: The arm is on the same side as a mastectomy
Venipuncture should never be performed on the arm on the same side as a mastectomy due to the risk of lymphedema and infection.
An arm on the same side as a mastectomy is contraindicated for venipuncture because lymph nodes may have been removed during surgery, causing impaired lymphatic drainage. Performing venipuncture on this arm increases the risk of lymphedema, infection, and compromised healing. Other contraindicated sites include arms with AV fistulas, areas with hematomas, edematous tissue, and areas near an active IV.
Question 6: After completing a venipuncture, what is the correct procedure for activating the safety device on the needle?
- Push the safety shield forward with the thumb using a one-handed technique (Correct answer)
- Remove the needle and manually cap it
- Pull the needle straight out and drop it immediately into the sharps container
- Ask the patient to hold the needle while you activate the device
Correct answer: Push the safety shield forward with the thumb using a one-handed technique
Safety needle devices should be activated using a one-handed technique, pushing the safety shield forward over the needle immediately after withdrawal.
OSHA's Bloodborne Pathogens Standard requires the use of safety-engineered devices. After withdrawing the needle, the phlebotomist should immediately activate the safety mechanism using a one-handed technique. Two-handed recapping of needles is prohibited because it is the leading cause of needlestick injuries. The entire assembly should then be disposed of in the sharps container without disassembly.
ASCP Phlebotomy 3
Which vein is the most commonly used site for routine venipuncture in adults?