Free CVA Laboratory Sample Handling 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?

Accepted Answer

Allow the tube to stand upright at room temperature for 30 minutes to clot.

Answer

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?

Accepted Answer

The patient's name, owner's name, and collection method.

Answer

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?

Accepted Answer

Parasite eggs may have hatched or larval forms may have degraded, leading to a false negative result.

Answer

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?

Accepted Answer

Using a spreader slide angle that is too high (e.g., 50 degrees).

Answer

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)?

Accepted Answer

Lavender (purple) top tube

Answer

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.

(CVA) Certified Veterinary Assistant Practice Test

(CVA) Certified Veterinary Assistant Practice Test

Free CVA Laboratory Sample Handling Questions and Answers