Basic Laboratory Procedures and Specimen Handling Flashcards

What is the correct temperature range for refrigerating urine specimens awaiting analysis?

Answer: 2°C to 8°C

Urine specimens must be refrigerated at 2°C to 8°C to preserve cellular elements and prevent bacterial overgrowth if not analyzed within one hour of collection.

Which type of specimen tube contains EDTA as an anticoagulant?

Answer: Lavender/purple top

Lavender (purple) top tubes contain EDTA (ethylenediaminetetraacetic acid), which chelates calcium to prevent clotting, making them ideal for complete blood counts (CBC).

What does a quality control (QC) chart help the medical assistant monitor in the laboratory?

Answer: Accuracy and precision of test results over time

QC charts (Levey-Jennings charts) plot control values over time to identify trends, shifts, or random errors that may indicate problems with reagents, instruments, or technique.

Which specimen is used for a fasting blood glucose test?

Answer: Serum or plasma from a venipuncture after 8–12 hours of fasting

A fasting blood glucose requires the patient to abstain from food and caloric beverages for 8–12 hours prior to collection; serum or plasma is then obtained by venipuncture.

What is the purpose of the chain of custody procedure for laboratory specimens?

Answer: To document every person who handled the specimen to ensure legal integrity

Chain of custody documents every individual who collected, transferred, or handled a specimen, ensuring legal defensibility particularly for drug testing, forensic, or workplace samples.

When centrifuging a blood specimen to obtain serum, what must occur before centrifugation?

Answer: The blood must be allowed to clot completely (30 minutes)

For serum separation, blood in a red-top or SST tube must clot fully (approximately 30 minutes at room temperature) before centrifugation; premature spinning yields incomplete serum separation.