VetSkill PCA Lab and Diagnostics Practice Test

For CBC and peripheral smear evaluation, you need a blood sample that stays unclotted and keeps cells in their normal shape. EDTA does just that by binding calcium, which prevents clotting, and it preserves red and white blood cell morphology so automated counts are accurate and smears show true cell details.

Red-top tubes are used for serum after clotting, which removes cells from the sample and can distort morphology. Heparin tubes can be used for some plasma tests but aren’t ideal for accurate CBC counts or for high-quality smear evaluation due to potential effects on cell morphology. Fluoride-oxalate tubes are designed to preserve glucose and aren’t meant for CBC or smear analysis, as they don’t maintain cell morphology as well as EDTA.

So EDTA tubes are the best choice for CBC and peripheral smear evaluation.