Laboratory Sample Handling Flashcards

When collecting a urine sample for culture and sensitivity, which collection method is preferred to avoid contamination?

Answer: Cystocentesis

Cystocentesis (needle aspiration directly from the bladder) provides the most sterile urine sample for bacterial culture, avoiding urethral and environmental contamination.

A fecal flotation test is used to detect which type of parasites?

Answer: Eggs and oocysts of intestinal parasites

Fecal flotation uses a high-density solution to float parasite eggs and oocysts to the surface for microscopic identification.

Which anticoagulant tube is used when collecting blood for a complete blood count (CBC)?

Answer: Purple/lavender top (EDTA)

EDTA (purple/lavender top) is the anticoagulant of choice for CBC because it best preserves cell morphology and prevents clotting without affecting cell counts.

How should a blood smear be stored if it cannot be stained immediately?

Answer: Air-dried and protected from dust and moisture

Blood smears should be air-dried quickly and stored in a clean, dry slide box to preserve cell morphology until staining.

What is the correct temperature for storing most urine samples awaiting analysis?

Answer: Refrigerated at 2–8°C

Urine samples should be refrigerated at 2–8°C to slow bacterial growth and cellular deterioration, ideally analyzed within 30–60 minutes of collection.

Which stain is most commonly used to perform a differential white blood cell count on a blood smear?

Answer: Wright-Giemsa stain

Wright-Giemsa stain differentiates white blood cell types by staining nuclear and cytoplasmic components different colors, enabling differential counts.

When is it necessary to use a gray-top (sodium fluoride/potassium oxalate) tube for blood collection?

Answer: For blood glucose measurement requiring delayed analysis

Gray-top tubes contain sodium fluoride, which inhibits glycolysis, preserving glucose levels in samples that cannot be analyzed immediately.