Basic Laboratory Procedures and Specimen Handling Flashcards
6 cards from real NCMA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Basic Laboratory Procedures and Specimen Handling flashcards as text
When performing a venipuncture, which color-topped tube should be drawn first if blood cultures are not ordered?
Answer: Light Blue
Following the standard order of draw to prevent cross-contamination of additives, the light blue top tube is drawn first after blood cultures. This tube contains sodium citrate and is used for coagulation studies, which are sensitive to other additives.
What is the additive in a lavender-topped tube and what is its purpose?
Answer: EDTA, to prevent clotting by binding calcium
The lavender (or purple) top tube contains the anticoagulant ethylenediaminetetraacetic acid (EDTA). EDTA works by binding to calcium in the blood, which prevents clotting and preserves the shape and structure of blood cells for hematology tests like a CBC.
A medical assistant is instructing a patient on how to collect a clean-catch midstream urine specimen. Which instruction is correct?
Answer: Wipe the area, begin to urinate in the toilet, then collect the sample.
A clean-catch midstream specimen requires careful cleansing of the genital area to prevent contamination. The patient should begin urinating into the toilet, then move the collection cup into the stream to collect the sample, and finally finish urinating in the toilet.
When is the most appropriate time to label a patient's specimen container?
Answer: Immediately after collection, in front of the patient.
To prevent errors, specimen containers must be labeled immediately after collection, in the presence of the patient. Pre-labeling containers or labeling them after leaving the room increases the risk of misidentification and medical errors.
What is the purpose of inverting a blood collection tube after it is filled?
Answer: To ensure proper mixing of the additive and the blood.
Tubes with additives, such as anticoagulants or clot activators, must be gently inverted a specific number of times. This action ensures that the additive is thoroughly mixed with the blood specimen to function correctly, either by preventing clotting or promoting it.
Which of the following is an example of a CLIA-waived test that a medical assistant might perform?
Answer: Urine dipstick test
CLIA-waived tests are simple laboratory examinations and procedures that have a low risk for an incorrect result. A urine dipstick test is a common example, as it is simple to perform and interpret. Blood cultures and PAP smears are complex tests requiring certified laboratories.