CCMA Phlebotomy Procedures 5

Question 1

A phlebotomist is collecting blood from a patient receiving a heparin infusion through an IV in the left antecubital fossa. The only available vein on the right arm is a small cephalic vein at the wrist. Which action is MOST appropriate?

Accepted Answer

Draw from the right wrist cephalic vein using a 23-gauge butterfly needle

Answer

When an IV is present and no suitable antecubital vein is accessible on the contralateral arm, collecting from a distal site (wrist/hand) on the non-IV arm using a butterfly needle is appropriate. Drawing below an active IV — even after a short pause — risks heparin contamination of the specimen, which would falsely alter coagulation studies and other analytes. A 2-minute pause is insufficient; CLSI guidelines recommend a minimum of 2 minutes after stopping the infusion AND discarding the first 5 mL if drawing below an IV, but the preferred approach is always to use the opposite extremity first.

Question 2

A patient's ethylenediaminetetraacetic acid (EDTA) tube shows platelet clumping on the peripheral blood smear, leading to a falsely low platelet count. Which alternative anticoagulant tube should the phlebotomist collect to obtain an accurate platelet count?

Accepted Answer

Sodium citrate (light blue top)

Answer

EDTA-dependent pseudothrombocytopenia is caused by antibodies that agglutinate platelets in the presence of EDTA at room temperature. Collecting a sodium citrate (light blue top) tube resolves this artifact because citrate inhibits platelet clumping via a different chelation mechanism. The laboratory can then correct the platelet count using the dilution factor (1:10 ratio of citrate to blood). Heparin can also reduce clumping but is less preferred for platelet counts due to its own interference. Gray tops inhibit glycolysis and are not used for hematologic analysis. Yellow tops (thrombin or ACD) are not indicated here.

Question 3

During a venipuncture on a patient with a suspected latex allergy, the phlebotomist discovers only standard latex tourniquet and latex gloves are available. The patient denies any previous severe reactions but reports mild skin irritation from latex products. What is the MOST appropriate course of action?

Accepted Answer

Use a blood pressure cuff inflated to below diastolic pressure as a tourniquet and obtain latex-free gloves before proceeding

Answer

Any reported latex sensitivity warrants full latex-free precautions, as repeated low-level exposures can sensitize patients to develop anaphylaxis. A blood pressure cuff inflated below diastolic pressure is an accepted alternative to a latex tourniquet and creates adequate venous distension. Latex-free gloves must be obtained before proceeding. Applying a latex tourniquet over clothing reduces but does not eliminate exposure risk and is not a recommended standard. Canceling the draw is unnecessary if latex-free alternatives are available elsewhere in the facility.

Question 4

A phlebotomist performs a capillary puncture on a neonate's heel for a PKU screening card. After warming the heel and performing the puncture, the first drop of blood is wiped away. The next drops are slow and the phlebotomist squeezes the heel repeatedly to fill the filter paper circles. What is the PRIMARY concern with this technique?

Accepted Answer

Tissue fluid dilution from squeezing will alter the concentration of analytes on the filter paper

Answer

Repeated squeezing of the heel forces interstitial tissue fluid into the blood sample, diluting the concentration of analytes such as phenylalanine, thyroid-stimulating hormone (TSH), and other newborn screening markers. This can produce false-negative results — a critical error for conditions like PKU or congenital hypothyroidism where early detection is life-saving. CLSI and newborn screening guidelines explicitly prohibit 'milking' or squeezing the site. If flow is inadequate, a new puncture on a freshly warmed site is required. Hemolysis is less relevant for dried blood spot testing than for liquid specimens.

Question 5

A phlebotomist draws a stat troponin, BMP, and PT/INR on an inpatient. When centrifuging the specimens, the SST tube (gold top) shows a partially clotted specimen with visible fibrin strands after 10 minutes of centrifugation. Which action is correct?

Accepted Answer

Recollect the SST tube; fibrin strands in the serum will interfere with immunoassay and chemistry analyzers

Answer

Fibrin strands in serum indicate incomplete clotting, which occurs when the specimen was not allowed to clot for the required 30 minutes at room temperature before centrifugation. Fibrin can physically clog analyzer probes, produce false results in immunoassays (including troponin), and cause erroneous electrolyte values. Re-centrifugation does not eliminate fibrin already present and risks platelet activation altering analyte values. Transferring serum with visible fibrin is not acceptable. The correct action is to recollect the tube, allow full clotting time (30 minutes), and re-centrifuge. For a stat troponin, notify the nurse of the delay.

CCMA - Certified Clinical Medical Assistant Practice Test

CCMA - Certified Clinical Medical Assistant Practice Test

CCMA Phlebotomy Procedures 5