Venipuncture Site Selection and Complications
Updated October 27, 2026
Routine Blood Collections is the biggest domain on the NHA CPT exam, and much of it comes down to two skills: choosing the right site and handling problems when they happen. Here’s what to know, followed by free practice questions. Collection questions on the exam follow the CLSI venipuncture standard; at work, always follow your facility’s procedure.
Choosing a vein
The veins of the antecubital area (the inside of the elbow) are the first choice for most venipunctures:
| Vein | Notes |
|---|---|
| Median cubital | First choice: large, well anchored and usually less painful |
| Cephalic | Second choice: on the thumb side, often easy to feel in heavier patients |
| Basilic | Last choice: on the pinky side, close to the brachial artery and a major nerve, and rolls easily |
If no antecubital vein is suitable, veins on the back of the hand can be used, usually with a smaller needle or a butterfly. Follow your facility’s policy before using any other site.
Sites to avoid
- The arm on the side of a mastectomy, unless the provider allows it
- An arm with an IV running (if there’s no other choice, follow your facility’s policy, which usually means drawing below the IV after it has been stopped for a set time)
- An arm with a fistula or graft for dialysis
- Scarred, burned, bruised or swollen areas, and areas with a hematoma
- Arteries: if you feel a pulse, it isn’t a vein
Tourniquet and technique basics
- Place the tourniquet about 3 to 4 inches above the site.
- Leave it on for no more than 1 minute. Longer can change test results (hemoconcentration).
- Insert the needle bevel up, at an angle of about 15 to 30 degrees.
- Release the tourniquet before removing the needle.
Complications and what to do
| Problem | What to do |
|---|---|
| Hematoma (swelling under the skin) | Stop: release the tourniquet, remove the needle and apply pressure |
| Patient feels faint (syncope) | Stop the draw, remove the needle, lower the patient’s head or have them lie down, and get help |
| Sharp, shooting or electric pain (possible nerve injury) | Stop immediately and remove the needle |
| Bright red blood that spurts (possible arterial puncture) | Remove the needle and apply firm pressure for at least 5 minutes |
| No blood flow | Adjust the needle slightly or try a new tube; don’t probe blindly. Follow your facility’s limit on attempts |
Free practice questions
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Which vein is usually the first choice for venipuncture?Answer: BThe median cubital vein is large, well anchored and usually the least painful, so it's the first choice. The basilic vein is last because it's close to an artery and a major nerve.
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What is the maximum time a tourniquet should stay on during a venipuncture?Answer: ALeaving the tourniquet on longer than 1 minute can cause hemoconcentration, which changes some test results.
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A patient had a mastectomy on the left side. Which arm should be used?Answer: CAvoid the arm on the side of a mastectomy, because lymph node removal raises the risk of swelling and infection. Use the other arm unless the provider gives other instructions.
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During a draw, the patient says they feel dizzy and light-headed. What should the phlebotomist do first?Answer: DThese are warning signs of fainting. Stop the procedure, release the tourniquet, remove the needle, protect the patient from falling and get help.
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Swelling forms quickly around the needle during a draw. What is happening, and what should be done?Answer: ARapid swelling means blood is leaking into the tissue. Stop the draw, remove the needle and apply pressure to limit the hematoma.
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A patient reports a sharp, electric pain down the arm as the needle goes in. What should the phlebotomist do?Answer: CSharp, shooting or electric pain may mean the needle has touched a nerve. Stop right away and remove the needle to avoid lasting injury, then follow your facility's reporting procedure.
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