AACC Specimen Collection & Processing Flashcards
6 cards from real AACC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 AACC Specimen Collection & Processing flashcards as text
What is the primary reason for inverting blood collection tubes gently after venipuncture?
Answer: To mix the additive thoroughly with the blood sample
Gentle inversion mixes the blood with the tube additive (anticoagulant, clot activator, or preservative) to ensure uniform distribution and proper sample preparation.
Which specimen type is required for coagulation testing (PT/INR, aPTT), and what is the critical blood-to-anticoagulant ratio?
Answer: Plasma from a light blue (sodium citrate) tube; 9:1 blood-to-anticoagulant ratio
Coagulation tests require citrated plasma (light blue tube) with a strict 9:1 blood-to-citrate ratio to ensure accurate calcium chelation and clotting factor activity.
What is the recommended storage condition for most routine chemistry specimens (serum/plasma) if testing is delayed beyond 8 hours?
Answer: Refrigeration at 2–8°C after separating from cells
Serum or plasma should be separated from cells and refrigerated at 2–8°C to slow metabolic activity and enzymatic degradation while maintaining analyte stability.
What does the term 'hemolysis index' refer to in automated chemistry analyzers?
Answer: A spectrophotometric measurement of free hemoglobin used to flag and quantify hemolysis
The hemolysis index is measured by the analyzer at 414 nm (oxyhemoglobin absorbance) to detect and quantify free hemoglobin released by lysed red blood cells.
For ammonia testing, which pre-analytical handling requirement is most critical?
Answer: Immediate chilling on ice and rapid transport to the laboratory
Ammonia is rapidly generated from amino acids and deamination at room temperature, so specimens must be chilled immediately on ice and analyzed within 15–30 minutes.
Which specimen is the gold standard for measuring true ionized calcium in critically ill patients?
Answer: Whole blood collected anaerobically in a heparinized syringe analyzed immediately
Ionized calcium must be measured in whole blood collected without air exposure (anaerobically), as CO2 escape raises pH and shifts calcium to the protein-bound form, lowering ionized values.