CVA Laboratory Techniques and Diagnostic Procedures 3 — Questions and Answers
Question 1: Which anticoagulant is used in a purple-top (EDTA) tube and works by chelating calcium?
- Heparin
- Sodium citrate
- EDTA (ethylenediaminetetraacetic acid) (Correct answer)
- Potassium oxalate
Correct answer: EDTA (ethylenediaminetetraacetic acid)
EDTA chelates (binds) calcium ions, preventing the coagulation cascade from activating, making purple-top tubes ideal for CBCs.
Question 2: When performing a urine specific gravity measurement with a refractometer, what solution is used to calibrate the instrument?
- Normal saline (0.9% NaCl)
- Distilled water (Correct answer)
- 5% dextrose solution
- Phosphate-buffered saline
Correct answer: Distilled water
Distilled water reads 1.000 on a refractometer, making it the correct calibration standard for urine specific gravity.
Question 3: A fecal flotation uses a solution with a specific gravity higher than parasite eggs to do what?
- Kill parasites so they can be safely handled
- Cause eggs to sink to the bottom of the tube
- Cause eggs to float to the surface for collection (Correct answer)
- Stain eggs for easier identification
Correct answer: Cause eggs to float to the surface for collection
High specific gravity flotation solutions are denser than parasite eggs, causing the eggs to rise and concentrate at the liquid surface under a coverslip.
Question 4: Which cell type, elevated in a CBC differential, is most commonly associated with allergic reactions and parasitic infections?
- Neutrophils
- Lymphocytes
- Eosinophils (Correct answer)
- Basophils
Correct answer: Eosinophils
Eosinophilia is classically linked to hypersensitivity (allergic) responses and parasitic infestations.
Question 5: What is the correct order of layers from top to bottom after centrifuging a hematocrit tube?
- Plasma, buffy coat, packed red blood cells (Correct answer)
- Packed red blood cells, buffy coat, plasma
- Buffy coat, plasma, packed red blood cells
- Plasma, packed red blood cells, buffy coat
Correct answer: Plasma, buffy coat, packed red blood cells
After centrifugation, plasma (least dense) sits on top, the buffy coat (WBCs/platelets) is in the middle, and packed RBCs (most dense) are at the bottom.
Question 6: A vaginal cytology smear showing primarily anuclear squamous (cornified) epithelial cells indicates which stage of the canine estrous cycle?
- Proestrus
- Estrus (Correct answer)
- Diestrus
- Anestrus
Correct answer: Estrus
During estrus, high estrogen levels cause maximal cornification of vaginal epithelium, producing >90% anuclear squamous cells on cytology.
Question 7: Which quality control step should be performed before running patient samples on a chemistry analyzer?
- Running a positive fecal control
- Running high and low control sera to verify calibration (Correct answer)
- Centrifuging the analyzer rotor
- Staining a blood smear with Diff-Quik
Correct answer: Running high and low control sera to verify calibration
Running high and low control sera verifies that the analyzer is calibrated correctly and results are within acceptable ranges before patient testing.
CVA Laboratory Techniques and Diagnostic Procedures 3
Which anticoagulant is used in a purple-top (EDTA) tube and works by chelating calcium?