Free CVA Laboratory Sample Handling Questions and Answers 1 — Questions and Answers
Question 1: A veterinary assistant is preparing a serum separator tube (SST) for analysis. After the blood is drawn, what is the correct next step to ensure proper separation of the serum?
- Centrifuge the tube immediately at high speed.
- Place the tube in the refrigerator for 10 minutes before centrifuging.
- Allow the tube to stand upright at room temperature for 30 minutes to clot. (Correct answer)
- Gently shake the tube for 15 seconds to mix the clot activator.
Correct answer: Allow the tube to stand upright at room temperature for 30 minutes to clot.
For a serum separator tube to work correctly, the blood must be allowed to form a complete clot before centrifugation. This process typically takes about 30 minutes at room temperature. Centrifuging too early or shaking the tube can result in an incomplete clot and a poor-quality serum sample.
Question 2: Which of the following is the most critical piece of information to include when labeling a urine sample collected via cystocentesis that will be sent to an external lab for culture?
- The time of day the sample was collected.
- The patient's name, owner's name, and collection method. (Correct answer)
- The patient's current medications.
- The volume of urine collected.
Correct answer: The patient's name, owner's name, and collection method.
While all details are helpful, the patient's name and owner's name are essential for positive identification. Indicating the collection method (cystocentesis) is critical for interpreting culture results, as it is the most sterile method and helps the lab differentiate between true infection and contamination.
Question 3: A client brings in a fecal sample for parasite analysis that has been in a sealed plastic bag in their warm car for the entire day. What is the primary concern with this sample?
- The sample will be too dry to process correctly.
- Zoonotic bacteria will have been killed by the heat.
- The plastic bag will have leached chemicals into the sample.
- Parasite eggs may have hatched or larval forms may have degraded, leading to a false negative result. (Correct answer)
Correct answer: Parasite eggs may have hatched or larval forms may have degraded, leading to a false negative result.
Fecal samples should be as fresh as possible or refrigerated if there is a delay. Exposure to heat for an extended period can cause helminth eggs to develop and hatch, or delicate protozoal cysts to degrade, making them undetectable and potentially leading to an inaccurate, false-negative diagnosis.
Question 4: When preparing a blood smear slide using the wedge technique, what is the most common cause of creating a smear that is too thick and short?
- Using a spreader slide angle that is too low (e.g., 25 degrees).
- Pushing the spreader slide too quickly.
- Using a spreader slide angle that is too high (e.g., 50 degrees). (Correct answer)
- Using a drop of blood that is too small.
Correct answer: Using a spreader slide angle that is too high (e.g., 50 degrees).
In the wedge technique for blood smear preparation, the angle of the spreader slide directly influences the thickness and length of the smear. A higher or steeper angle (greater than 45 degrees) will create a smear that is thicker and shorter. A lower angle produces a thinner, longer smear.
Question 5: Which of the following blood collection tubes contains EDTA as the anticoagulant and is primarily used for a Complete Blood Count (CBC)?
- Green top tube
- Red top tube
- Blue top tube
- Lavender (purple) top tube (Correct answer)
Correct answer: Lavender (purple) top tube
The lavender (or purple) top tube contains Ethylenediaminetetraacetic acid (EDTA), which is the preferred anticoagulant for hematology because it preserves cell morphology and prevents clotting by chelating calcium. Green top tubes contain heparin, red tops have no anticoagulant (or a clot activator), and blue tops contain sodium citrate for coagulation studies.
Question 6: A veterinary assistant is packaging a blood sample to be shipped to a diagnostic laboratory. According to standard guidelines, what constitutes the 'triple packaging' system?
- A plastic bag, an envelope, and a cardboard box.
- A leak-proof primary container, a leak-proof secondary container with absorbent material, and a rigid outer box. (Correct answer)
- The blood tube, a padded envelope, and a biohazard bag.
- A styrofoam cooler, bubble wrap, and a sealed plastic container.
Correct answer: A leak-proof primary container, a leak-proof secondary container with absorbent material, and a rigid outer box.
Shipping regulations for biological specimens require a triple packaging system to prevent leaks and ensure safety. This consists of: 1) a securely sealed, leak-proof primary container (the blood tube itself), 2) a leak-proof secondary container (like a sealed bag or jar) with enough absorbent material to contain any potential spill, and 3) a durable, rigid outer package for transport.
Free CVA Laboratory Sample Handling Questions and Answers 1
A veterinary assistant is preparing a serum separator tube (SST) for analysis.
After the blood is drawn, what is the correct next step to ensure proper separation of the serum?