Phlebotomy Exam Questions & Answers 2026 (21–30)

Question 1

A patient presents with lymphedema of the left arm following a mastectomy. The right antecubital veins are sclerosed from chemotherapy. Which action is most appropriate?

TheoryPractice · Accepted Answer

Consult the ordering physician or nursing staff for an approved alternative site before proceeding. Both lymphedema and sclerosed veins are contraindications requiring the phlebotomist to seek guidance rather than defaulting to a compromised site unilaterally.

Question 2

Which formed element of blood is anucleate, biconcave, and survives approximately 120 days in circulation?

TheoryPractice · Accepted Answer

Erythrocyte. Mature erythrocytes (red blood cells) lack a nucleus and most organelles, adopt a biconcave disc shape, and have an average lifespan of about 120 days before being removed by the spleen.

Question 3

During venipuncture of the basilic vein, a patient suddenly reports sharp, shooting pain radiating down the forearm to the fingers. What is the most likely explanation?

TheoryPractice · Accepted Answer

The needle has inadvertently contacted the median nerve, which runs near the basilic vein. The basilic vein lies in close proximity to the medial cutaneous nerve and, in some individuals, branches of the median nerve; needle contact can produce sharp radicular pain, making this vein a higher-risk site.

Question 4

Serum differs from plasma in that serum lacks which component?

TheoryPractice · Accepted Answer

Fibrinogen and clotting factors consumed during coagulation. Serum is the liquid fraction remaining after blood has clotted; the clotting process consumes fibrinogen and other coagulation factors, which are therefore absent from serum but present in plasma.

Question 5

A phlebotomist notes that a patient's veins feel hard and cord-like along the median cubital area. This finding is most consistent with which condition?

TheoryPractice · Accepted Answer

Sclerosis (fibrosis) due to repeated venipuncture or thrombophlebitis. Repeated puncture or prior inflammation causes scar tissue to form within the vein wall, making it feel hard and cord-like — a sclerosed vein should be avoided as it is difficult to access and increases the risk of failed collection.

Question 6

Platelets (thrombocytes) are derived from large precursor cells in the bone marrow called:

TheoryPractice · Accepted Answer

Megakaryocytes. Megakaryocytes are giant polyploid cells in the bone marrow that shed cytoplasmic fragments to produce platelets, which are essential for primary hemostasis.

Question 7

When a tourniquet is left in place longer than one minute before venipuncture, which laboratory analyte is most likely to show a falsely elevated result?

TheoryPractice · Accepted Answer

Total protein. Prolonged tourniquet application causes hemoconcentration by restricting venous outflow, which increases the concentration of large molecules like proteins that cannot leave the vascular space, leading to falsely elevated total protein results.

Question 8

A phlebotomist is collecting blood from the antecubital fossa and notices the needle bevel is correctly placed but blood flow stops abruptly. Repositioning slightly restores flow. Which anatomical explanation best accounts for this pattern?

TheoryPractice · Accepted Answer

The bevel has occluded against the posterior wall of the vein lumen. When the needle is advanced too far or the vein collapses slightly, the bevel can press against the vessel wall and occlude flow; slight withdrawal or rotation of the needle realigns the bevel within the lumen and restores draw.

Question 9

The antecubital basilic vein is considered a third-choice site compared to the median cubital and cephalic veins. Beyond nerve proximity, which additional anatomical factor increases its risk?

TheoryPractice · Accepted Answer

It lies deeper and closer to the brachial artery than the other antecubital veins. The basilic vein sits more medially and deeply, in closer anatomical proximity to the brachial artery and the medial nerve bundle, increasing the risk of inadvertent arterial puncture or nerve injury compared with the more superficial and laterally situated alternatives.

Question 10

Which granulocyte is the predominant white blood cell in a healthy adult's differential count and is the first responder to bacterial infection?

TheoryPractice · Accepted Answer

Neutrophil. Neutrophils constitute roughly 50–70% of circulating leukocytes in healthy adults and are the primary phagocytes that arrive first at sites of acute bacterial infection via chemotaxis.

Phlebotomy Exam Questions & Answers 2026 (21–30)

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