Laboratory Procedures and Specimen Collection Flashcards

When performing a venipuncture, what is the correct order of draw if a light blue, a lavender, and a red top tube are needed?

Answer: Light Blue, Red, Lavender

The correct order of draw is critical to prevent cross-contamination of additives between tubes. The standard order is: blood cultures, light blue (coagulation), red/gold (serum), green (heparin), lavender (EDTA), and gray (glycolytic inhibitor). Therefore, the correct sequence is light blue, red, then lavender.

The additive in a lavender-topped blood collection tube is:

Answer: EDTA

Lavender (or purple) top tubes contain the anticoagulant Ethylenediaminetetraacetic acid (EDTA). EDTA works by binding to calcium in the blood, which prevents the coagulation cascade and preserves the blood cells for hematology tests like a complete blood count (CBC).

In a routine urinalysis, what does the specific gravity of the urine measure?

Answer: The concentration of dissolved particles

Specific gravity measures the concentration of dissolved solutes in the urine, reflecting the kidney's ability to concentrate urine. A high specific gravity indicates concentrated urine (possible dehydration), while a low specific gravity indicates dilute urine.

Which of the following is considered a CLIA-waived test that a medical assistant can perform?

Answer: Rapid streptococcus test

CLIA-waived tests are simple laboratory examinations and procedures that have an insignificant risk of an erroneous result. A rapid streptococcus test, or 'rapid strep,' is a common example of a CLIA-waived test performed in many medical offices.

How should a medical assistant handle a blood specimen for a bilirubin test?

Answer: It must be protected from light

Bilirubin is photosensitive, meaning it breaks down when exposed to light. To ensure an accurate test result, specimens for bilirubin testing must be protected from light by wrapping the tube in foil or using an amber-colored collection tube.

The most common and preferred site for routine venipuncture in adults is the:

Answer: Median cubital vein

The median cubital vein, located in the antecubital fossa (the bend of the elbow), is the most common site for venipuncture. It is typically large, well-anchored, and close to the surface, making it the easiest and safest vein to access.

When collecting a throat swab for a rapid strep test, the medical assistant should swab the:

Answer: Posterior pharynx and tonsils

To obtain an adequate sample for a throat culture or rapid strep test, the swab should be directed to the posterior pharynx and the tonsillar areas. It is important to avoid touching the tongue, cheeks, or uvula to prevent contamination of the sample.